diff --git a/.formatter.exs b/.formatter.exs
new file mode 100644
index 0000000..c83945f
--- /dev/null
+++ b/.formatter.exs
@@ -0,0 +1,8 @@
+[
+  import_deps: [:phoenix],
+  inputs: ["*.{ex,exs}", "{config,lib,test}/**/*.{ex,exs}"],
+  locals_without_parens: [
+    field: :*,
+    belongs_to: :*
+  ]
+]
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d8847ff
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,36 @@
+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where 3rd-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+stripe_mock-*.tar
+
+# Since we are building assets from assets/,
+# we ignore priv/static. You may want to comment
+# this depending on your deployment strategy.
+/priv/static/
+
+# Files matching config/*.secret.exs pattern contain sensitive
+# data and you should not commit them into version control.
+#
+# Alternatively, you may comment the line below and commit the
+# secrets files as long as you replace their contents by environment
+# variables.
+/config/*.secret.exs
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..f217df0
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2019 Nick Kezhaya
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..683d42e
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+# StripeMock
+
+Starts a server that pretends to be Stripe. Docs here: https://hexdocs.pm/stripe_mock/StripeMock.html
diff --git a/config/config.exs b/config/config.exs
new file mode 100644
index 0000000..0a8e523
--- /dev/null
+++ b/config/config.exs
@@ -0,0 +1,28 @@
+# This file is responsible for configuring your application
+# and its dependencies with the aid of the Mix.Config module.
+#
+# This configuration file is loaded before any dependency and
+# is restricted to this project.
+
+# General application configuration
+use Mix.Config
+
+# Configures the endpoint
+config :stripe_mock, StripeMockWeb.Endpoint,
+  url: [host: "localhost"],
+  http: [:inet6, port: System.get_env("PORT") || 12111],
+  secret_key_base: "ug9ATr9o7f/N2inxnW+SlrNVP7Ok+f9gAP43yHfqqm/bgFZSLeY6vQOY+wp562Iz",
+  render_errors: [view: StripeMockWeb.ErrorView, accepts: ~w(json)],
+  pubsub: [name: StripeMock.PubSub, adapter: Phoenix.PubSub.PG2]
+
+# Configures Elixir's Logger
+config :logger, :console,
+  format: "$time $metadata[$level] $message\n",
+  metadata: [:request_id]
+
+# Use Jason for JSON parsing in Phoenix
+config :phoenix, :json_library, Jason
+
+# Import environment specific config. This must remain at the bottom
+# of this file so it overrides the configuration defined above.
+import_config "#{Mix.env()}.exs"
diff --git a/config/dev.exs b/config/dev.exs
new file mode 100644
index 0000000..55f2e1c
--- /dev/null
+++ b/config/dev.exs
@@ -0,0 +1,47 @@
+use Mix.Config
+
+# For development, we disable any cache and enable
+# debugging and code reloading.
+#
+# The watchers configuration can be used to run external
+# watchers to your application. For example, we use it
+# with webpack to recompile .js and .css sources.
+config :stripe_mock, StripeMockWeb.Endpoint,
+  debug_errors: true,
+  code_reloader: true,
+  check_origin: false,
+  watchers: []
+
+# ## SSL Support
+#
+# In order to use HTTPS in development, a self-signed
+# certificate can be generated by running the following
+# Mix task:
+#
+#     mix phx.gen.cert
+#
+# Note that this task requires Erlang/OTP 20 or later.
+# Run `mix help phx.gen.cert` for more information.
+#
+# The `http:` config above can be replaced with:
+#
+#     https: [
+#       port: 4001,
+#       cipher_suite: :strong,
+#       keyfile: "priv/cert/selfsigned_key.pem",
+#       certfile: "priv/cert/selfsigned.pem"
+#     ],
+#
+# If desired, both `http:` and `https:` keys can be
+# configured to run both http and https servers on
+# different ports.
+
+# Do not include metadata nor timestamps in development logs
+config :logger, :console, format: "[$level] $message\n"
+
+# Set a higher stacktrace during development. Avoid configuring such
+# in production as building large stacktraces may be expensive.
+config :phoenix, :stacktrace_depth, 20
+
+# Initialize plugs at runtime for faster development compilation
+config :phoenix, :plug_init_mode, :runtime
diff --git a/config/test.exs b/config/test.exs
new file mode 100644
index 0000000..d03ae72
--- /dev/null
+++ b/config/test.exs
@@ -0,0 +1,7 @@
+use Mix.Config
+
+config :stripe_mock, StripeMockWeb.Endpoint,
+  server: false
+
+# Print only warnings and errors during test
+config :logger, level: :warn
diff --git a/lib/stripe_mock.ex b/lib/stripe_mock.ex
new file mode 100644
index 0000000..0ab2671
--- /dev/null
+++ b/lib/stripe_mock.ex
@@ -0,0 +1,27 @@
+defmodule StripeMock do
+  @moduledoc """
+  StripeMock is a service that duplicates some of the core functionality of the
+  Stripe API, without doing enough to receive a cease-and-desist letter from
+  Stripe's legal team.
+
+  This has been created for testing purposes only. MY GOD will it speed up your
+  test suite.
+
+  First, add the dependency to your `mix.exs`:
+
+      {:stripe_mock, "~> 0.1.0"}
+
+  (or whatever the latest version is; I probably won't be updating this moduledoc.)
+
+  In your app's `config/test.exs` file:
+
+      config :stripity_stripe, :api_base_url, "http://localhost:12111/v1/"
+      config :stripe_mock, StripeMockWeb.Endpoint, http: [port: 12111], server: true
+
+  That should get the StripeMock server to start in your test environment.
+
+  No database connection is needed. `StripeMock.Repo` is just a GenServer that
+  stores everything in its state. It'd be nice if `ecto_mnesia` was updated for
+  Ecto 3, but as of right now this is the next best option.
+  """
+end
diff --git a/lib/stripe_mock/api.ex b/lib/stripe_mock/api.ex
new file mode 100644
index 0000000..27f4af2
--- /dev/null
+++ b/lib/stripe_mock/api.ex
@@ -0,0 +1,39 @@
+defmodule StripeMock.API do
+  alias StripeMock.API.Operations, as: Ops
+
+  # Customers
+  defdelegate list_customers(), to: Ops.Customer
+  defdelegate get_customer(id), to: Ops.Customer
+  defdelegate get_customer!(id), to: Ops.Customer
+  defdelegate create_customer(attrs \\ %{}), to: Ops.Customer
+  defdelegate update_customer(customer, attrs \\ %{}), to: Ops.Customer
+  defdelegate delete_customer(customer), to: Ops.Customer
+
+  # Tokens
+  defdelegate get_token(id), to: Ops.Token
+  defdelegate create_token(attrs \\ %{}), to: Ops.Token
+
+  # Cards
+  defdelegate list_cards(customer), to: Ops.Card
+  defdelegate get_card!(id), to: Ops.Card
+  defdelegate create_card(customer, attrs \\ %{}), to: Ops.Card
+  defdelegate create_customer_card_from_source(customer, source, metadata \\ %{}), to: Ops.Card
+  defdelegate update_card(card, attrs \\ %{}), to: Ops.Card
+  defdelegate delete_card(card), to: Ops.Card
+
+  # Sources - TODO
+  # defdelegate attach_source(source, customer), to: Ops.Source
+  # defdelegate detach_source(source, customer), to: Ops.Source
+
+  # Charges
+  defdelegate list_charges(), to: Ops.Charge
+  defdelegate get_charge(id), to: Ops.Charge
+  defdelegate create_charge(attrs \\ %{}), to: Ops.Charge
+  defdelegate update_charge(charge, attrs \\ %{}), to: Ops.Charge
+
+  # Refunds
+  defdelegate list_refunds(), to: Ops.Refund
+  defdelegate get_refund(id), to: Ops.Refund
+  defdelegate create_refund(attrs \\ %{}), to: Ops.Refund
+  defdelegate update_refund(refund, attrs \\ %{}), to: Ops.Refund
+end
diff --git a/lib/stripe_mock/api/card.ex b/lib/stripe_mock/api/card.ex
new file mode 100644
index 0000000..2be5fca
--- /dev/null
+++ b/lib/stripe_mock/api/card.ex
@@ -0,0 +1,79 @@
+defmodule StripeMock.API.Card do
+  use Ecto.Schema
+  import Ecto.Changeset
+  alias StripeMock.API
+
+  schema "cards" do
+    field :brand, :string
+    field :created, :integer
+    field :deleted, :boolean
+    field :metadata, StripeMock.Metadata, default: %{}
+    field :last4, :string
+    field :source, :string
+
+    field :number, :string
+    field :exp_month, :integer
+    field :exp_year, :integer
+    field :cvc, :string
+
+    belongs_to :customer, API.Customer
+  end
+
+  @doc false
+  def create_changeset(card, attrs) do
+    card
+    |> cast(attrs, [:source, :metadata])
+    |> validate_required([:source, :metadata])
+    |> set_brand()
+    |> set_last4()
+  end
+
+  @doc false
+  def update_changeset(card, attrs) do
+    card
+    |> cast(attrs, [])
+    |> validate_required([])
+  end
+
+  @doc false
+  def token_changeset(card, attrs) do
+    card
+    |> cast(attrs, [:number, :exp_month, :exp_year, :cvc])
+    |> validate_required([:number, :exp_month, :exp_year, :cvc])
+    |> set_brand()
+    |> set_last4()
+  end
+
+  defp set_brand(changeset) do
+    brand =
+      case get_field(changeset, :number) do
+        "4242424242424242" -> "Visa"
+        "4000056655665556" -> "Visa"
+        "5555555555554444" -> "Mastercard"
+        "2223003122003222" -> "Mastercard"
+        "5200828282828210" -> "Mastercard"
+        "5105105105105100" -> "Mastercard"
+        "378282246310005" -> "American Express"
+        "371449635398431" -> "American Express"
+        "6011111111111117" -> "Discover"
+        "6011000990139424" -> "Discover"
+        "30569309025904" -> "Diners Club"
+        "38520000023237" -> "Diners Club"
+        "3566002020360505" -> "JCB"
+        "6200000000000005" -> "UnionPay"
+      end
+
+    put_change(changeset, :brand, brand)
+  end
+
+  defp set_last4(changeset) do
+    case get_field(changeset, :number) do
+      number when is_bitstring(number) ->
+        last4 = String.split_at(number, -6) |> elem(1)
+        put_change(changeset, :last4, last4)
+
+      _ ->
+        changeset
+    end
+  end
+end
diff --git a/lib/stripe_mock/api/charge.ex b/lib/stripe_mock/api/charge.ex
new file mode 100644
index 0000000..dbe2c42
--- /dev/null
+++ b/lib/stripe_mock/api/charge.ex
@@ -0,0 +1,47 @@
+defmodule StripeMock.API.Charge do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  alias StripeMock.API
+
+  @foreign_key_type :binary_id
+  schema "charges" do
+    field :amount, :integer
+    field :capture, :boolean, default: false
+    field :currency, :string
+    field :description, :string
+    field :metadata, StripeMock.Metadata, default: %{}
+    field :statement_descriptor, :string
+    field :transfer_group, :string
+
+    belongs_to :customer, API.Customer
+  end
+
+  @doc false
+  def create_changeset(charge, attrs) do
+    charge
+    |> cast(attrs, [
+      :amount,
+      :currency,
+      :capture,
+      :customer_id,
+      :description,
+      :metadata,
+      :statement_descriptor,
+      :transfer_group
+    ])
+    |> validate_required([:amount, :currency])
+  end
+
+  @doc false
+  def update_changeset(charge, attrs) do
+    charge
+    |> cast(attrs, [
+      :customer_id,
+      :description,
+      :metadata,
+      :transfer_group
+    ])
+    |> validate_required([:amount, :currency])
+  end
+end
diff --git a/lib/stripe_mock/api/customer.ex b/lib/stripe_mock/api/customer.ex
new file mode 100644
index 0000000..a8b3eb3
--- /dev/null
+++ b/lib/stripe_mock/api/customer.ex
@@ -0,0 +1,30 @@
+defmodule StripeMock.API.Customer do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @primary_key {:id, :binary_id, autogenerate: false}
+  schema "customers" do
+    field :created, :integer
+    field :currency, :string, default: "usd"
+    field :deleted, :boolean, default: false
+    field :description, :string
+    field :email, :string
+    field :metadata, StripeMock.Metadata, default: %{}
+    field :name, :string
+    field :phone, :string
+  end
+
+  @doc false
+  def changeset(customer, attrs) do
+    customer
+    |> cast(attrs, [:created, :currency, :description, :email, :name, :phone])
+    |> validate_email()
+  end
+
+  defp validate_email(changeset) do
+    case get_field(changeset, :email) do
+      nil -> changeset
+      _ -> validate_format(changeset, :email, ~r/.+@.+\..+/i)
+    end
+  end
+end
diff --git a/lib/stripe_mock/api/operations/card.ex b/lib/stripe_mock/api/operations/card.ex
new file mode 100644
index 0000000..ff47a2b
--- /dev/null
+++ b/lib/stripe_mock/api/operations/card.ex
@@ -0,0 +1,41 @@
+defmodule StripeMock.API.Operations.Card do
+  alias StripeMock.Repo
+  alias StripeMock.API.Card
+
+  def list_cards(customer) do
+    Card
+    |> Repo.all()
+    |> Enum.filter(&(&1.customer_id == customer.id))
+  end
+
+  def get_card!(id), do: Repo.get!(Card, id)
+
+  def create_card(customer, attrs) do
+    %Card{customer_id: customer.id}
+    |> Card.create_changeset(attrs)
+    |> Repo.insert()
+  end
+
+  def create_customer_card_from_source(customer, source, metadata) do
+    result =
+      source.card
+      |> Ecto.Changeset.change(%{customer_id: customer.id, metadata: metadata})
+      |> Repo.update()
+
+    source
+    |> Ecto.Changeset.change(%{used: true})
+    |> Repo.update()
+
+    result
+  end
+
+  def update_card(%Card{} = card, attrs) do
+    card
+    |> Card.update_changeset(attrs)
+    |> Repo.update()
+  end
+
+  def delete_card(%Card{} = card) do
+    Repo.delete(card)
+  end
+end
diff --git a/lib/stripe_mock/api/operations/charge.ex b/lib/stripe_mock/api/operations/charge.ex
new file mode 100644
index 0000000..bb8a44b
--- /dev/null
+++ b/lib/stripe_mock/api/operations/charge.ex
@@ -0,0 +1,24 @@
+defmodule StripeMock.API.Operations.Charge do
+  alias StripeMock.Repo
+  alias StripeMock.API.Charge
+
+  def list_charges do
+    Repo.all(Charge)
+  end
+
+  def get_charge(id) do
+    Repo.fetch(Charge, id)
+  end
+
+  def create_charge(attrs \\ %{}) do
+    %Charge{}
+    |> Charge.create_changeset(attrs)
+    |> Repo.insert()
+  end
+
+  def update_charge(%Charge{} = charge, attrs) do
+    charge
+    |> Charge.create_changeset(attrs)
+    |> Repo.update()
+  end
+end
diff --git a/lib/stripe_mock/api/operations/customer.ex b/lib/stripe_mock/api/operations/customer.ex
new file mode 100644
index 0000000..3368c42
--- /dev/null
+++ b/lib/stripe_mock/api/operations/customer.ex
@@ -0,0 +1,33 @@
+defmodule StripeMock.API.Operations.Customer do
+  alias StripeMock.Repo
+  alias StripeMock.API.Customer
+
+  def list_customers() do
+    Repo.all(Customer)
+  end
+
+  def get_customer(id) do
+    case Repo.get(Customer, id) do
+      nil -> {:error, :not_found}
+      customer -> {:ok, customer}
+    end
+  end
+
+  def get_customer!(id), do: Repo.get!(Customer, id)
+
+  def create_customer(attrs \\ %{}) do
+    %Customer{}
+    |> Customer.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  def update_customer(%Customer{} = customer, attrs) do
+    customer
+    |> Customer.changeset(attrs)
+    |> Repo.update()
+  end
+
+  def delete_customer(%Customer{} = customer) do
+    Repo.delete(customer)
+  end
+end
diff --git a/lib/stripe_mock/api/operations/refund.ex b/lib/stripe_mock/api/operations/refund.ex
new file mode 100644
index 0000000..84e8491
--- /dev/null
+++ b/lib/stripe_mock/api/operations/refund.ex
@@ -0,0 +1,24 @@
+defmodule StripeMock.API.Operations.Refund do
+  alias StripeMock.Repo
+  alias StripeMock.API.Refund
+
+  def list_refunds do
+    Repo.all(Refund)
+  end
+
+  def get_refund(id) do
+    Repo.fetch(Refund, id)
+  end
+
+  def create_refund(attrs \\ %{}) do
+    %Refund{}
+    |> Refund.create_changeset(attrs)
+    |> Repo.insert()
+  end
+
+  def update_refund(%Refund{} = refund, attrs) do
+    refund
+    |> Refund.update_changeset(attrs)
+    |> Repo.update()
+  end
+end
diff --git a/lib/stripe_mock/api/operations/token.ex b/lib/stripe_mock/api/operations/token.ex
new file mode 100644
index 0000000..52ea324
--- /dev/null
+++ b/lib/stripe_mock/api/operations/token.ex
@@ -0,0 +1,14 @@
+defmodule StripeMock.API.Operations.Token do
+  alias StripeMock.Repo
+  alias StripeMock.API.Token
+
+  def get_token(id) do
+    Repo.fetch(Token, id)
+  end
+
+  def create_token(attrs) do
+    %Token{}
+    |> Token.changeset(attrs)
+    |> Repo.insert()
+  end
+end
diff --git a/lib/stripe_mock/api/refund.ex b/lib/stripe_mock/api/refund.ex
new file mode 100644
index 0000000..9dd8801
--- /dev/null
+++ b/lib/stripe_mock/api/refund.ex
@@ -0,0 +1,78 @@
+defmodule StripeMock.API.Refund do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  alias StripeMock.{API, Repo}
+
+  @foreign_key_type :binary_id
+  schema "refunds" do
+    field :amount, :integer
+    field :metadata, StripeMock.Metadata, default: %{}
+    field :reason, :string
+
+    belongs_to :charge, API.Charge
+  end
+
+  @doc false
+  def create_changeset(refund, attrs) do
+    refund
+    |> cast(attrs, [:charge_id, :amount, :metadata, :reason])
+    |> validate_required([:charge_id])
+    |> set_default_amount()
+    |> validate_required(:amount)
+    |> validate_amount()
+    |> validate_reason()
+  end
+
+  @doc false
+  def update_changeset(refund, attrs) do
+    refund
+    |> cast(attrs, [:metadata])
+  end
+
+  defp set_default_amount(changeset) do
+    with nil <- get_field(changeset, :amount),
+         {:ok, charge} <- fetch_charge(changeset) do
+      put_change(changeset, :amount, charge.amount)
+    else
+      _ -> changeset
+    end
+  end
+
+  defp validate_amount(changeset) do
+    with {:ok, charge} <- fetch_charge(changeset),
+         amount when is_integer(amount) <- get_field(changeset, :amount) do
+      total_refunded =
+        __MODULE__
+        |> Repo.all()
+        |> Enum.filter(&(&1.charge_id == charge.id))
+        |> Enum.map(& &1.amount)
+        |> Enum.sum()
+
+      if total_refunded + amount > charge.amount do
+        add_error(changeset, :amount, "is too high")
+      else
+        changeset
+      end
+    else
+      _ -> changeset
+    end
+  end
+
+  defp validate_reason(changeset) do
+    case get_field(changeset, :reason) do
+      nil -> changeset
+      reason when reason in ~w(duplicate fraudulent requested_by_customer) -> changeset
+      _ -> add_error(changeset, :reason, "is invalid")
+    end
+  end
+
+  defp fetch_charge(changeset) do
+    with charge_id when is_bitstring(charge_id) <- get_field(changeset, :charge_id),
+         {:ok, _} = result <- Repo.fetch(API.Charge, charge_id) do
+      result
+    else
+      _ -> nil
+    end
+  end
+end
diff --git a/lib/stripe_mock/api/token.ex b/lib/stripe_mock/api/token.ex
new file mode 100644
index 0000000..3cae8e1
--- /dev/null
+++ b/lib/stripe_mock/api/token.ex
@@ -0,0 +1,31 @@
+defmodule StripeMock.API.Token do
+  use Ecto.Schema
+  import Ecto.Changeset
+  alias StripeMock.API
+
+  @foreign_key_type :binary_id
+  schema "tokens" do
+    field :client_ip, :string
+    field :created, :integer
+    field :type, :string
+    field :used, :boolean, default: false
+
+    belongs_to :card, API.Card
+  end
+
+  @doc false
+  def changeset(token, attrs) do
+    token
+    |> cast(attrs, [:client_ip])
+    |> cast_assoc(:card, with: &API.Card.token_changeset/2)
+    |> set_type()
+    |> validate_required([:client_ip, :type])
+  end
+
+  defp set_type(changeset) do
+    case get_field(changeset, :card) do
+      nil -> changeset
+      _ -> put_change(changeset, :type, "card")
+    end
+  end
+end
diff --git a/lib/stripe_mock/application.ex b/lib/stripe_mock/application.ex
new file mode 100644
index 0000000..b6a4e3f
--- /dev/null
+++ b/lib/stripe_mock/application.ex
@@ -0,0 +1,20 @@
+defmodule StripeMock.Application do
+  @moduledoc false
+
+  use Application
+
+  def start(_type, _args) do
+    children = [
+      StripeMockWeb.Endpoint,
+      StripeMock.Repo
+    ]
+
+    opts = [strategy: :one_for_one, name: StripeMock.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+
+  def config_change(changed, _new, removed) do
+    StripeMockWeb.Endpoint.config_change(changed, removed)
+    :ok
+  end
+end
diff --git a/lib/stripe_mock/base52.ex b/lib/stripe_mock/base52.ex
new file mode 100644
index 0000000..665f565
--- /dev/null
+++ b/lib/stripe_mock/base52.ex
@@ -0,0 +1,25 @@
+defmodule StripeMock.Base52 do
+  @chars '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
+  @base52_alphabet @chars -- 'AEIOUaeiou'
+
+  @doc """
+  Encodes an integer into a base52 string.
+
+      iex> encode(0)
+      "0"
+      iex> encode(1000000000)
+      "2clyTD"
+  """
+  def encode(0), do: "0"
+
+  def encode(integer) when is_integer(integer) do
+    do_encode(integer, '') |> to_string()
+  end
+
+  defp do_encode(integer, encoded) when integer > 0 do
+    encoded = [Enum.at(@base52_alphabet, rem(integer, 52)) | encoded]
+    do_encode(Integer.floor_div(integer, 52), encoded)
+  end
+
+  defp do_encode(0, encoded), do: encoded
+end
diff --git a/lib/stripe_mock/error.ex b/lib/stripe_mock/error.ex
new file mode 100644
index 0000000..f55c75a
--- /dev/null
+++ b/lib/stripe_mock/error.ex
@@ -0,0 +1,25 @@
+defmodule StripeMock.Error do
+  defstruct [:code, :message, :param, :type]
+
+  @type t() :: %__MODULE__{
+          code: atom(),
+          message: String.t(),
+          param: nil | map(),
+          type: atom()
+        }
+
+  def unauthorized() do
+    %__MODULE__{
+      code: :unauthorized,
+      message: "Unauthorized",
+      param: nil,
+      type: :unauthorized
+    }
+  end
+
+  def http_status(%__MODULE__{code: :resource_missing, param: "id"}),
+    do: 404
+
+  def http_status(%__MODULE__{code: :resource_missing}),
+    do: 400
+end
diff --git a/lib/stripe_mock/id.ex b/lib/stripe_mock/id.ex
new file mode 100644
index 0000000..84f6e4e
--- /dev/null
+++ b/lib/stripe_mock/id.ex
@@ -0,0 +1,12 @@
+defmodule StripeMock.ID do
+  @moduledoc """
+  Generates a somewhat Stripe-esque random ID string. Pretty much a base52-encoded UUID.
+  """
+
+  def generate() do
+    :crypto.strong_rand_bytes(16)
+    |> :erlang.binary_to_list()
+    |> Enum.reduce(1, &(&1 * &2))
+    |> StripeMock.Base52.encode()
+  end
+end
diff --git a/lib/stripe_mock/metadata.ex b/lib/stripe_mock/metadata.ex
new file mode 100644
index 0000000..681ba9d
--- /dev/null
+++ b/lib/stripe_mock/metadata.ex
@@ -0,0 +1,27 @@
+defmodule StripeMock.Metadata do
+  @behaviour Ecto.Type
+
+  def type(), do: :map
+
+  def cast(nil), do: {:ok, %{}}
+  def cast(""), do: {:ok, %{}}
+
+  def cast(metadata) when is_map(metadata) do
+    value =
+      for {k, v} <- metadata,
+          is_bitstring(k) and String.length(k) <= 40,
+          is_bitstring(v) and String.length(v) <= 500,
+          into: %{},
+          do: {k, v}
+
+    {:ok, value}
+  end
+
+  def cast(_), do: :error
+
+  def dump(value) when is_map(value), do: {:ok, value}
+  def dump(_), do: :error
+
+  def load(value) when is_map(value), do: {:ok, value}
+  def load(_), do: :error
+end
diff --git a/lib/stripe_mock/pagination.ex b/lib/stripe_mock/pagination.ex
new file mode 100644
index 0000000..5dd98d1
--- /dev/null
+++ b/lib/stripe_mock/pagination.ex
@@ -0,0 +1,43 @@
+defmodule StripeMock.Pagination do
+  @moduledoc """
+  Handles the Stripe-esque pagination.
+  """
+
+  alias __MODULE__.Page
+
+  defmacro __using__(_opts) do
+    quote do
+      def render_page(conn, page, view, template) do
+        %{
+          object: "list",
+          url: "/v1/customers",
+          has_more: page.has_more,
+          data: render_many(page.data, view, template)
+        }
+      end
+    end
+  end
+
+  @spec paginate(list(), map()) :: Page.t()
+  def paginate(objects, params) do
+    limit = get_limit(params)
+
+    objects =
+      case params["starting_after"] do
+        nil -> objects
+        starting_after -> Enum.drop_while(objects, &(&1.id != starting_after))
+      end
+
+    %Page{data: Enum.take(objects, limit), has_more: length(objects) > limit}
+  end
+
+  @default_limit 10
+  defp get_limit(%{"limit" => limit}) do
+    case Integer.parse(limit) do
+      {limit, ""} -> max(limit, 1)
+      _ -> @default_limit
+    end
+  end
+
+  defp get_limit(_params), do: @default_limit
+end
diff --git a/lib/stripe_mock/pagination/page.ex b/lib/stripe_mock/pagination/page.ex
new file mode 100644
index 0000000..d16d4bc
--- /dev/null
+++ b/lib/stripe_mock/pagination/page.ex
@@ -0,0 +1,13 @@
+defmodule StripeMock.Pagination.Page do
+  @moduledoc """
+  Defines a `Page` type for passing data to the views.
+  """
+
+  @enforce_keys [:has_more, :data]
+  defstruct [:has_more, :data]
+
+  @type t() :: %__MODULE__{
+          has_more: boolean(),
+          data: list()
+        }
+end
diff --git a/lib/stripe_mock/repo.ex b/lib/stripe_mock/repo.ex
new file mode 100644
index 0000000..29b537f
--- /dev/null
+++ b/lib/stripe_mock/repo.ex
@@ -0,0 +1,175 @@
+defmodule StripeMock.Repo do
+  @moduledoc """
+  This is where we store everything. Obviously, don't call any of these
+  functions yourself.
+
+  State structure is:
+
+      %{
+        customers: %{
+          "cus_123123" => %Customer{}
+        }
+      }
+  """
+  use GenServer
+  import Ecto.Changeset
+  alias Ecto.Changeset
+  alias StripeMock.API
+
+  def start_link(opts \\ []) do
+    GenServer.start_link(__MODULE__, %{}, [name: __MODULE__] ++ opts)
+  end
+
+  def all(schema), do: GenServer.call(pid(), {:all, schema})
+  def insert(changeset), do: GenServer.call(pid(), {:save, changeset})
+  def update(changeset), do: GenServer.call(pid(), {:save, changeset})
+  def get(schema, id), do: GenServer.call(pid(), {:get, schema, id})
+
+  def get!(schema, id) do
+    case GenServer.call(pid(), {:get, schema, id}) do
+      nil -> raise "Not found."
+      record -> record
+    end
+  end
+
+  def fetch(schema, id) do
+    case get(schema, id) do
+      nil -> {:error, :not_found}
+      object -> {:ok, object}
+    end
+  end
+
+  def delete(%Changeset{} = changeset) do
+    changeset = put_change(changeset, :deleted, true)
+    GenServer.call(pid(), {:save, changeset})
+  end
+
+  def delete(object), do: GenServer.call(pid(), {:save, %{object | deleted: true}})
+
+  defp pid(), do: GenServer.whereis(__MODULE__)
+
+  @impl true
+  def init(state) do
+    {:ok, state}
+  end
+
+  @impl true
+  def handle_call({:all, schema}, _from, state) do
+    case Map.get(state, schema) do
+      schemas when is_map(schemas) -> {:reply, Map.values(schemas), state}
+      _ -> {:reply, [], state}
+    end
+  end
+
+  @impl true
+  def handle_call({:save, changeset}, _from, state) do
+    case save(changeset, state) do
+      {:ok, term, new_state} -> {:reply, {:ok, term}, new_state}
+      {:error, _} = error -> {:reply, error, state}
+    end
+  end
+
+  @impl true
+  def handle_call({:get, schema, id}, _from, state) do
+    object =
+      with schemas when is_map(schemas) <- Map.get(state, schema),
+           object when is_map(object) <- Map.get(schemas, id) do
+        object
+      else
+        _ -> nil
+      end
+
+    {:reply, object, state}
+  end
+
+  @spec save(Changeset.t(), map()) :: {:ok, any(), map()} | {:error, Changeset.t()}
+  defp save(changeset, state) do
+    changeset = change(changeset)
+
+    changeset =
+      case get_field(changeset, :id) do
+        nil -> put_change(changeset, :id, generate_id(changeset.data))
+        id when is_bitstring(id) -> changeset
+      end
+
+    changeset =
+      cond do
+        Map.has_key?(changeset.data, :created) ->
+          case get_field(changeset, :created) do
+            nil -> put_change(changeset, :created, :os.system_time(:seconds))
+            _ -> changeset
+          end
+
+        true ->
+          changeset
+      end
+
+    changeset =
+      if Map.has_key?(changeset.data, :object) do
+        put_change(changeset, :object, type(changeset.data))
+      else
+        changeset
+      end
+
+    # Run through changed assocs and save
+    {changeset, state} =
+      Enum.reduce_while(changeset.changes, {changeset, state}, fn
+        {key, %Changeset{} = assoc_change}, {changeset, state} ->
+          case save(assoc_change, state) do
+            {:ok, saved_assoc, new_state} ->
+              changeset =
+                changeset
+                |> put_change(key, saved_assoc)
+                |> put_change(String.to_atom("#{key}_id"), saved_assoc.id)
+
+              {:cont, {changeset, new_state}}
+
+            {:error, failed_assoc} ->
+              changeset = put_change(changeset, key, failed_assoc)
+              throw({:invalid_changeset, changeset})
+          end
+
+        _, acc ->
+          {:cont, acc}
+      end)
+
+    if !changeset.valid? do
+      throw({:invalid_changeset, changeset})
+    end
+
+    object = apply_changes(changeset)
+
+    # Put the object into the new state
+    type = object.__struct__
+
+    type_map =
+      case Map.get(state, type) do
+        %{} = s -> s
+        _ -> %{}
+      end
+      |> Map.put(object.id, object)
+
+    new_state = Map.put(state, type, type_map)
+
+    {:ok, object, new_state}
+  catch
+    {:invalid_changeset, changeset} ->
+      {:error, changeset}
+  end
+
+  defp generate_id(schema) do
+    prefix(schema) <> "_" <> StripeMock.ID.generate()
+  end
+
+  def type(%API.Card{}), do: :card
+  def type(%API.Charge{}), do: :charge
+  def type(%API.Customer{}), do: :customer
+  def type(%API.Refund{}), do: :refund
+  def type(%API.Token{}), do: :token
+
+  def prefix(%API.Card{}), do: "card"
+  def prefix(%API.Charge{}), do: "ch"
+  def prefix(%API.Customer{}), do: "cus"
+  def prefix(%API.Refund{}), do: "re"
+  def prefix(%API.Token{}), do: "tok"
+end
diff --git a/lib/stripe_mock_web.ex b/lib/stripe_mock_web.ex
new file mode 100644
index 0000000..c1ffa35
--- /dev/null
+++ b/lib/stripe_mock_web.ex
@@ -0,0 +1,71 @@
+defmodule StripeMockWeb do
+  @moduledoc """
+  The entrypoint for defining your web interface, such
+  as controllers, views, channels and so on.
+
+  This can be used in your application as:
+
+      use StripeMockWeb, :controller
+      use StripeMockWeb, :view
+
+  The definitions below will be executed for every view,
+  controller, etc, so keep them short and clean, focused
+  on imports, uses and aliases.
+
+  Do NOT define functions inside the quoted expressions
+  below. Instead, define any helper function in modules
+  and import those modules here.
+  """
+
+  def controller do
+    quote do
+      use Phoenix.Controller, namespace: StripeMockWeb
+
+      import Plug.Conn
+      import StripeMockWeb.Gettext
+      import StripeMock.Pagination, only: [paginate: 2]
+      alias StripeMockWeb.Router.Helpers, as: Routes
+      alias StripeMockWeb.Plug, as: SMPlug
+    end
+  end
+
+  def view do
+    quote do
+      use Phoenix.View,
+        root: "lib/stripe_mock_web/templates",
+        namespace: StripeMockWeb
+
+      use StripeMock.Pagination
+
+      # Import convenience functions from controllers
+      import Phoenix.Controller, only: [get_flash: 1, get_flash: 2, view_module: 1]
+
+      import StripeMockWeb.ErrorHelpers
+      import StripeMockWeb.ViewHelpers
+      import StripeMockWeb.Gettext
+      alias StripeMockWeb.Router.Helpers, as: Routes
+    end
+  end
+
+  def router do
+    quote do
+      use Phoenix.Router
+      import Plug.Conn
+      import Phoenix.Controller
+    end
+  end
+
+  def channel do
+    quote do
+      use Phoenix.Channel
+      import StripeMockWeb.Gettext
+    end
+  end
+
+  @doc """
+  When used, dispatch to the appropriate controller/view/etc.
+  """
+  defmacro __using__(which) when is_atom(which) do
+    apply(__MODULE__, which, [])
+  end
+end
diff --git a/lib/stripe_mock_web/controllers/charge_controller.ex b/lib/stripe_mock_web/controllers/charge_controller.ex
new file mode 100644
index 0000000..1fda950
--- /dev/null
+++ b/lib/stripe_mock_web/controllers/charge_controller.ex
@@ -0,0 +1,36 @@
+defmodule StripeMockWeb.ChargeController do
+  use StripeMockWeb, :controller
+
+  alias StripeMock.API
+  alias StripeMock.API.Charge
+
+  plug SMPlug.ConvertParams, %{"customer" => "customer_id"} when action in [:create, :update]
+  action_fallback StripeMockWeb.FallbackController
+
+  def index(conn, params) do
+    page = API.list_charges() |> paginate(params)
+    render(conn, "index.json", page: page)
+  end
+
+  def create(conn, charge_params) do
+    with {:ok, %Charge{} = charge} <- API.create_charge(charge_params) do
+      conn
+      |> put_status(:created)
+      |> put_resp_header("location", Routes.charge_path(conn, :show, charge))
+      |> render("show.json", charge: charge)
+    end
+  end
+
+  def show(conn, %{"id" => id}) do
+    with {:ok, charge} <- API.get_charge(id) do
+      render(conn, "show.json", charge: charge)
+    end
+  end
+
+  def update(conn, %{"id" => id} = charge_params) do
+    with {:ok, charge} <- API.get_charge(id),
+         {:ok, %Charge{} = charge} <- API.update_charge(charge, charge_params) do
+      render(conn, "show.json", charge: charge)
+    end
+  end
+end
diff --git a/lib/stripe_mock_web/controllers/customer_controller.ex b/lib/stripe_mock_web/controllers/customer_controller.ex
new file mode 100644
index 0000000..a52e073
--- /dev/null
+++ b/lib/stripe_mock_web/controllers/customer_controller.ex
@@ -0,0 +1,43 @@
+defmodule StripeMockWeb.CustomerController do
+  use StripeMockWeb, :controller
+
+  alias StripeMock.API
+  alias StripeMock.API.Customer
+
+  action_fallback StripeMockWeb.FallbackController
+
+  def index(conn, params) do
+    page = API.list_customers() |> paginate(params)
+    render(conn, "index.json", page: page)
+  end
+
+  def create(conn, customer_params) do
+    with {:ok, %Customer{} = customer} <- API.create_customer(customer_params) do
+      conn
+      |> put_status(:created)
+      |> put_resp_header("location", Routes.customer_path(conn, :show, customer))
+      |> render("show.json", customer: customer)
+    end
+  end
+
+  def show(conn, %{"id" => id}) do
+    customer = API.get_customer!(id)
+    render(conn, "show.json", customer: customer)
+  end
+
+  def update(conn, %{"id" => id} = customer_params) do
+    customer = API.get_customer!(id)
+
+    with {:ok, %Customer{} = customer} <- API.update_customer(customer, customer_params) do
+      render(conn, "show.json", customer: customer)
+    end
+  end
+
+  def delete(conn, %{"id" => id}) do
+    customer = API.get_customer!(id)
+
+    with {:ok, %Customer{}} <- API.delete_customer(customer) do
+      send_resp(conn, :no_content, "")
+    end
+  end
+end
diff --git a/lib/stripe_mock_web/controllers/fallback_controller.ex b/lib/stripe_mock_web/controllers/fallback_controller.ex
new file mode 100644
index 0000000..6baf637
--- /dev/null
+++ b/lib/stripe_mock_web/controllers/fallback_controller.ex
@@ -0,0 +1,30 @@
+defmodule StripeMockWeb.FallbackController do
+  @moduledoc """
+  Translates controller action results into valid `Plug.Conn` responses.
+
+  See `Phoenix.Controller.action_fallback/1` for more details.
+  """
+  use StripeMockWeb, :controller
+  alias StripeMock.Error
+
+  def call(conn, {:error, %Ecto.Changeset{} = changeset}) do
+    conn
+    |> put_status(:unprocessable_entity)
+    |> put_view(StripeMockWeb.ChangesetView)
+    |> render("error.json", changeset: changeset)
+  end
+
+  def call(conn, {:error, :not_found}) do
+    conn
+    |> put_status(:not_found)
+    |> put_view(StripeMockWeb.ErrorView)
+    |> render(:"404")
+  end
+
+  def call(conn, {:error, %Error{} = error}) do
+    conn
+    |> put_status(Error.http_status(error))
+    |> put_view(StripeMockWeb.ErrorView)
+    |> render(:error, error: error)
+  end
+end
diff --git a/lib/stripe_mock_web/controllers/refund_controller.ex b/lib/stripe_mock_web/controllers/refund_controller.ex
new file mode 100644
index 0000000..944e1fd
--- /dev/null
+++ b/lib/stripe_mock_web/controllers/refund_controller.ex
@@ -0,0 +1,36 @@
+defmodule StripeMockWeb.RefundController do
+  use StripeMockWeb, :controller
+
+  alias StripeMock.API
+  alias StripeMock.API.Refund
+
+  plug SMPlug.ConvertParams, %{"charge" => "charge_id"} when action in [:create, :update]
+  action_fallback StripeMockWeb.FallbackController
+
+  def index(conn, params) do
+    page = API.list_refunds() |> paginate(params)
+    render(conn, "index.json", page: page)
+  end
+
+  def create(conn, refund_params) do
+    with {:ok, %Refund{} = refund} <- API.create_refund(refund_params) do
+      conn
+      |> put_status(:created)
+      |> put_resp_header("location", Routes.refund_path(conn, :show, refund))
+      |> render("show.json", refund: refund)
+    end
+  end
+
+  def show(conn, %{"id" => id}) do
+    with {:ok, refund} <- API.get_refund(id) do
+      render(conn, "show.json", refund: refund)
+    end
+  end
+
+  def update(conn, %{"id" => id} = refund_params) do
+    with {:ok, refund} <- API.get_refund(id),
+         {:ok, %Refund{} = refund} <- API.update_refund(refund, refund_params) do
+      render(conn, "show.json", refund: refund)
+    end
+  end
+end
diff --git a/lib/stripe_mock_web/controllers/source_controller.ex b/lib/stripe_mock_web/controllers/source_controller.ex
new file mode 100644
index 0000000..2422860
--- /dev/null
+++ b/lib/stripe_mock_web/controllers/source_controller.ex
@@ -0,0 +1,74 @@
+defmodule StripeMockWeb.SourceController do
+  use StripeMockWeb, :controller
+
+  alias StripeMock.API
+
+  plug :set_customer when action != :show
+  action_fallback StripeMockWeb.FallbackController
+
+  # GET /v1/customers/cus_F7ux2fMKFvhMMP/sources?object=card
+  def index(conn, %{"object" => "card"} = params) do
+    page = API.list_cards(conn.assigns.customer) |> paginate(params)
+
+    conn
+    |> put_view(StripeMockWeb.CardView)
+    |> render("index.json", page: page)
+  end
+
+  # POST /v1/customers/cus_F9PeLuQPxok2xa/sources
+  def create(conn, %{"source" => token} = params) do
+    %{customer: customer} = conn.assigns
+
+    case API.get_token(token) do
+      {:ok, source} ->
+        with {:ok, source} <-
+               API.create_customer_card_from_source(customer, source, params["metadata"]) do
+          conn
+          |> put_status(:created)
+          |> render("show.json", source: source)
+        end
+
+      {:error, :not_found} ->
+        {:error,
+         %StripeMock.Error{code: :resource_missing, type: :invalid_request_error, param: "source"}}
+    end
+  end
+
+  def show(conn, %{"id" => id}) do
+    card = API.get_card!(id)
+
+    conn
+    |> put_view(StripeMockWeb.CardView)
+    |> render("show.json", card: card)
+  end
+
+  def update(conn, %{"id" => id, "card" => card_params}) do
+    card = API.get_card!(id)
+
+    with {:ok, source} <- API.update_card(card, card_params) do
+      render(conn, "show.json", source: source)
+    end
+  end
+
+  def delete(conn, %{"id" => id}) do
+    card = API.get_card!(id)
+
+    with {:ok, source} <- API.delete_card(card) do
+      render(conn, "show.json", source: source)
+    end
+  end
+
+  defp set_customer(%{params: %{"customer_id" => customer_id}} = conn, _arg) do
+    case API.get_customer(customer_id) do
+      {:ok, customer} ->
+        assign(conn, :customer, customer)
+
+      _ ->
+        conn
+        |> put_status(404)
+        |> put_view(StripeMockWeb.ErrorView)
+        |> render(:"404", [])
+        |> halt()
+    end
+  end
+end
diff --git a/lib/stripe_mock_web/controllers/token_controller.ex b/lib/stripe_mock_web/controllers/token_controller.ex
new file mode 100644
index 0000000..bb79297
--- /dev/null
+++ b/lib/stripe_mock_web/controllers/token_controller.ex
@@ -0,0 +1,22 @@
+defmodule StripeMockWeb.TokenController do
+  use StripeMockWeb, :controller
+
+  alias StripeMock.API
+
+  action_fallback StripeMockWeb.FallbackController
+  plug SMPlug.SetClientIP
+
+  def create(conn, params) do
+    with {:ok, token} <- API.create_token(params) do
+      conn
+      |> put_status(:created)
+      |> render("show.json", token: token)
+    end
+  end
+
+  def show(conn, %{"id" => id}) do
+    with {:ok, token} <- API.get_token(id) do
+      render(conn, "show.json", token: token)
+    end
+  end
+end
diff --git a/lib/stripe_mock_web/endpoint.ex b/lib/stripe_mock_web/endpoint.ex
new file mode 100644
index 0000000..9e7ef25
--- /dev/null
+++ b/lib/stripe_mock_web/endpoint.ex
@@ -0,0 +1,16 @@
+defmodule StripeMockWeb.Endpoint do
+  use Phoenix.Endpoint, otp_app: :stripe_mock
+
+  plug Plug.RequestId
+  plug Plug.Logger
+
+  plug Plug.Parsers,
+    parsers: [:urlencoded, :multipart, :json],
+    pass: ["*/*"],
+    json_decoder: Phoenix.json_library()
+
+  plug Plug.MethodOverride
+  plug Plug.Head
+
+  plug StripeMockWeb.Router
+end
diff --git a/lib/stripe_mock_web/gettext.ex b/lib/stripe_mock_web/gettext.ex
new file mode 100644
index 0000000..254ba79
--- /dev/null
+++ b/lib/stripe_mock_web/gettext.ex
@@ -0,0 +1,24 @@
+defmodule StripeMockWeb.Gettext do
+  @moduledoc """
+  A module providing Internationalization with a gettext-based API.
+
+  By using [Gettext](https://hexdocs.pm/gettext),
+  your module gains a set of macros for translations, for example:
+
+      import StripeMockWeb.Gettext
+
+      # Simple translation
+      gettext("Here is the string to translate")
+
+      # Plural translation
+      ngettext("Here is the string to translate",
+               "Here are the strings to translate",
+               3)
+
+      # Domain-based translation
+      dgettext("errors", "Here is the error message to translate")
+
+  See the [Gettext Docs](https://hexdocs.pm/gettext) for detailed usage.
+  """
+  use Gettext, otp_app: :stripe_mock
+end
diff --git a/lib/stripe_mock_web/plug/auth.ex b/lib/stripe_mock_web/plug/auth.ex
new file mode 100644
index 0000000..916abc4
--- /dev/null
+++ b/lib/stripe_mock_web/plug/auth.ex
@@ -0,0 +1,54 @@
+defmodule StripeMockWeb.Plug.Auth do
+  @moduledoc """
+  Pretends to do auth stuff.
+  """
+
+  use Phoenix.Controller
+
+  def init(options), do: options
+
+  def call(conn, _arg) do
+    if authed?(conn) do
+      conn
+    else
+      conn
+      |> put_status(:unauthorized)
+      |> put_view(StripeMockWeb.ErrorView)
+      |> render(:error, error: StripeMock.Error.unauthorized())
+      |> halt()
+    end
+  end
+
+  defp authed?(conn) do
+    case get_key(conn) do
+      "sk_test_" <> _ -> true
+      _ -> false
+    end
+  end
+
+  defp get_key(conn) do
+    conn.req_headers
+    |> Enum.find_value(fn
+      {"authorization", auth} when is_bitstring(auth) ->
+        case String.downcase(auth) do
+          "basic " <> _ ->
+            {_, base64_key} = String.split_at(auth, 6)
+
+            case Base.decode64(base64_key) do
+              {:ok, key} -> key
+              _ -> false
+            end
+
+          "bearer " <> _ ->
+            {_, key} = String.split_at(auth, 7)
+            key
+
+          _ ->
+            false
+        end
+
+      _ ->
+        false
+    end)
+  end
+end
diff --git a/lib/stripe_mock_web/plug/convert_params.ex b/lib/stripe_mock_web/plug/convert_params.ex
new file mode 100644
index 0000000..3680701
--- /dev/null
+++ b/lib/stripe_mock_web/plug/convert_params.ex
@@ -0,0 +1,24 @@
+defmodule StripeMockWeb.Plug.ConvertParams do
+  @moduledoc """
+  Moves params from one key to the other before they hit the changeset
+  functions. For example, `%{"customer_id" => customer_id}` should be changed
+  to `%{"customer" => customer_id}` for setting the customer in a way Stripe
+  would expect.
+  """
+
+  def init(options) when is_map(options) do
+    options
+  end
+
+  def call(conn, conversions) do
+    params =
+      for {k, v} <- conn.params, into: %{} do
+        case Map.get(conversions, k) do
+          nil -> {k, v}
+          new_key -> {new_key, v}
+        end
+      end
+
+    %{conn | params: params}
+  end
+end
diff --git a/lib/stripe_mock_web/plug/set_client_ip.ex b/lib/stripe_mock_web/plug/set_client_ip.ex
new file mode 100644
index 0000000..e0936d1
--- /dev/null
+++ b/lib/stripe_mock_web/plug/set_client_ip.ex
@@ -0,0 +1,13 @@
+defmodule StripeMockWeb.Plug.SetClientIP do
+  @moduledoc """
+  Sets the client IP address in the params via an extremely frowned upon method.
+  """
+
+  def init(options), do: options
+
+  def call(%{params: params} = conn, _arg) do
+    [a, b, c, d | _] = Tuple.to_list(conn.remote_ip)
+    params = Map.put(params, "client_ip", "#{a}.#{b}.#{c}.#{d}")
+    %{conn | params: params}
+  end
+end
diff --git a/lib/stripe_mock_web/router.ex b/lib/stripe_mock_web/router.ex
new file mode 100644
index 0000000..b5ec4ce
--- /dev/null
+++ b/lib/stripe_mock_web/router.ex
@@ -0,0 +1,21 @@
+defmodule StripeMockWeb.Router do
+  use StripeMockWeb, :router
+
+  pipeline :api do
+    plug :accepts, ["json"]
+    plug StripeMockWeb.Plug.Auth
+  end
+
+  scope "/v1", StripeMockWeb do
+    pipe_through :api
+
+    resources "/customers", CustomerController do
+      resources "/sources", SourceController
+    end
+
+    resources "/charges", ChargeController, except: [:delete]
+    resources "/refunds", RefundController, except: [:delete]
+    resources "/sources", SourceController, only: [:show]
+    resources "/tokens", TokenController, only: [:create, :show]
+  end
+end
diff --git a/lib/stripe_mock_web/view_helpers.ex b/lib/stripe_mock_web/view_helpers.ex
new file mode 100644
index 0000000..5ed8ff7
--- /dev/null
+++ b/lib/stripe_mock_web/view_helpers.ex
@@ -0,0 +1,7 @@
+defmodule StripeMockWeb.ViewHelpers do
+  def as_map(struct) do
+    struct
+    |> Map.delete(:__struct__)
+    |> Map.delete(:__meta__)
+  end
+end
diff --git a/lib/stripe_mock_web/views/card_view.ex b/lib/stripe_mock_web/views/card_view.ex
new file mode 100644
index 0000000..da8578c
--- /dev/null
+++ b/lib/stripe_mock_web/views/card_view.ex
@@ -0,0 +1,23 @@
+defmodule StripeMockWeb.CardView do
+  use StripeMockWeb, :view
+  alias __MODULE__
+
+  def render("index.json", %{conn: conn, page: page}) do
+    render_page(conn, page, CardView, "card.json")
+  end
+
+  def render("show.json", %{card: card}) do
+    render_one(card, CardView, "card.json")
+  end
+
+  def render("card.json", %{card: card}) do
+    card
+    |> Map.take(~w(id created deleted exp_month exp_year metadata last4 brand)a)
+    |> Map.put("object", "card")
+    |> Map.put("customer", card.customer_id)
+  end
+
+  def render("delete.json", %{card: card}) do
+    %{id: card.id, object: card.object, deleted: card.deleted}
+  end
+end
diff --git a/lib/stripe_mock_web/views/changeset_view.ex b/lib/stripe_mock_web/views/changeset_view.ex
new file mode 100644
index 0000000..2260fce
--- /dev/null
+++ b/lib/stripe_mock_web/views/changeset_view.ex
@@ -0,0 +1,19 @@
+defmodule StripeMockWeb.ChangesetView do
+  use StripeMockWeb, :view
+
+  @doc """
+  Traverses and translates changeset errors.
+
+  See `Ecto.Changeset.traverse_errors/2` and
+  `StripeMockWeb.ErrorHelpers.translate_error/1` for more details.
+  """
+  def translate_errors(changeset) do
+    Ecto.Changeset.traverse_errors(changeset, &translate_error/1)
+  end
+
+  def render("error.json", %{changeset: changeset}) do
+    # When encoded, the changeset returns its errors
+    # as a JSON object. So we just pass it forward.
+    %{errors: translate_errors(changeset)}
+  end
+end
diff --git a/lib/stripe_mock_web/views/charge_view.ex b/lib/stripe_mock_web/views/charge_view.ex
new file mode 100644
index 0000000..4679e97
--- /dev/null
+++ b/lib/stripe_mock_web/views/charge_view.ex
@@ -0,0 +1,27 @@
+defmodule StripeMockWeb.ChargeView do
+  use StripeMockWeb, :view
+  alias StripeMockWeb.ChargeView
+
+  def render("index.json", %{page: page}) do
+    %{data: render_many(page.data, ChargeView, "charge.json")}
+  end
+
+  def render("show.json", %{charge: charge}) do
+    render_one(charge, ChargeView, "charge.json")
+  end
+
+  def render("charge.json", %{charge: charge}) do
+    %{
+      id: charge.id,
+      amount: charge.amount,
+      currency: charge.currency,
+      capture: charge.capture,
+      customer: charge.customer_id,
+      description: charge.description,
+      metadata: charge.metadata,
+      object: "charge",
+      statement_descriptor: charge.statement_descriptor,
+      transfer_group: charge.transfer_group
+    }
+  end
+end
diff --git a/lib/stripe_mock_web/views/customer_view.ex b/lib/stripe_mock_web/views/customer_view.ex
new file mode 100644
index 0000000..1e5b841
--- /dev/null
+++ b/lib/stripe_mock_web/views/customer_view.ex
@@ -0,0 +1,16 @@
+defmodule StripeMockWeb.CustomerView do
+  use StripeMockWeb, :view
+  alias StripeMockWeb.CustomerView
+
+  def render("index.json", %{conn: conn, page: page}) do
+    render_page(conn, page, CustomerView, "customer.json")
+  end
+
+  def render("show.json", %{customer: customer}) do
+    render_one(customer, CustomerView, "customer.json")
+  end
+
+  def render("customer.json", %{customer: customer}) do
+    customer |> as_map()
+  end
+end
diff --git a/lib/stripe_mock_web/views/error_helpers.ex b/lib/stripe_mock_web/views/error_helpers.ex
new file mode 100644
index 0000000..831fc59
--- /dev/null
+++ b/lib/stripe_mock_web/views/error_helpers.ex
@@ -0,0 +1,33 @@
+defmodule StripeMockWeb.ErrorHelpers do
+  @moduledoc """
+  Conveniences for translating and building error messages.
+  """
+
+  @doc """
+  Translates an error message using gettext.
+  """
+  def translate_error({msg, opts}) do
+    # When using gettext, we typically pass the strings we want
+    # to translate as a static argument:
+    #
+    #     # Translate "is invalid" in the "errors" domain
+    #     dgettext("errors", "is invalid")
+    #
+    #     # Translate the number of files with plural rules
+    #     dngettext("errors", "1 file", "%{count} files", count)
+    #
+    # Because the error messages we show in our forms and APIs
+    # are defined inside Ecto, we need to translate them dynamically.
+    # This requires us to call the Gettext module passing our gettext
+    # backend as first argument.
+    #
+    # Note we use the "errors" domain, which means translations
+    # should be written to the errors.po file. The :count option is
+    # set by Ecto and indicates we should also apply plural rules.
+    if count = opts[:count] do
+      Gettext.dngettext(StripeMockWeb.Gettext, "errors", msg, msg, count, opts)
+    else
+      Gettext.dgettext(StripeMockWeb.Gettext, "errors", msg, opts)
+    end
+  end
+end
diff --git a/lib/stripe_mock_web/views/error_view.ex b/lib/stripe_mock_web/views/error_view.ex
new file mode 100644
index 0000000..4f59f1b
--- /dev/null
+++ b/lib/stripe_mock_web/views/error_view.ex
@@ -0,0 +1,20 @@
+defmodule StripeMockWeb.ErrorView do
+  use StripeMockWeb, :view
+
+  # If you want to customize a particular status code
+  # for a certain format, you may uncomment below.
+  # def render("500.json", _assigns) do
+  #   %{errors: %{detail: "Internal Server Error"}}
+  # end
+
+  # By default, Phoenix returns the status message from
+  # the template name. For example, "404.json" becomes
+  # "Not Found".
+  def template_not_found(template, _assigns) do
+    %{errors: %{detail: Phoenix.Controller.status_message_from_template(template)}}
+  end
+
+  def render("error.json", %{error: error}) do
+    %{error: Map.take(error, [:code, :message, :param, :type])}
+  end
+end
diff --git a/lib/stripe_mock_web/views/refund_view.ex b/lib/stripe_mock_web/views/refund_view.ex
new file mode 100644
index 0000000..9391827
--- /dev/null
+++ b/lib/stripe_mock_web/views/refund_view.ex
@@ -0,0 +1,22 @@
+defmodule StripeMockWeb.RefundView do
+  use StripeMockWeb, :view
+  alias StripeMockWeb.RefundView
+
+  def render("index.json", %{conn: conn, page: page}) do
+    render_page(conn, page, RefundView, "refund.json")
+  end
+
+  def render("show.json", %{refund: refund}) do
+    render_one(refund, RefundView, "refund.json")
+  end
+
+  def render("refund.json", %{refund: refund}) do
+    %{
+      id: refund.id,
+      charge: refund.charge_id,
+      amount: refund.amount,
+      metadata: refund.metadata,
+      reason: refund.reason
+    }
+  end
+end
diff --git a/lib/stripe_mock_web/views/source_view.ex b/lib/stripe_mock_web/views/source_view.ex
new file mode 100644
index 0000000..e0a607b
--- /dev/null
+++ b/lib/stripe_mock_web/views/source_view.ex
@@ -0,0 +1,10 @@
+defmodule StripeMockWeb.SourceView do
+  use StripeMockWeb, :view
+
+  def render("show.json", %{source: source}) do
+    case source.id do
+      "card_" <> _ -> render_one(source, StripeMockWeb.CardView, "card.json")
+      _ -> raise "Weird ID"
+    end
+  end
+end
diff --git a/lib/stripe_mock_web/views/token_view.ex b/lib/stripe_mock_web/views/token_view.ex
new file mode 100644
index 0000000..8df98ce
--- /dev/null
+++ b/lib/stripe_mock_web/views/token_view.ex
@@ -0,0 +1,30 @@
+defmodule StripeMockWeb.TokenView do
+  use StripeMockWeb, :view
+  alias StripeMockWeb.{CardView, TokenView}
+
+  def render("index.json", %{conn: conn, page: page}) do
+    render_page(conn, page, TokenView, "token.json")
+  end
+
+  def render("show.json", %{token: token}) do
+    render_one(token, TokenView, "token.json")
+  end
+
+  def render("token.json", %{token: token}) do
+    object = %{
+      id: token.id,
+      object: "token",
+      client_ip: token.client_ip,
+      created: token.created,
+      type: token.type,
+      used: token.used
+    }
+
+    if token.card do
+      card = render(CardView, "card.json", card: token.card)
+      Map.put(object, :card, card)
+    else
+      object
+    end
+  end
+end
diff --git a/mix.exs b/mix.exs
new file mode 100644
index 0000000..1e5da9a
--- /dev/null
+++ b/mix.exs
@@ -0,0 +1,61 @@
+defmodule StripeMock.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :stripe_mock,
+      version: "0.1.0",
+      elixir: "~> 1.5",
+      elixirc_paths: elixirc_paths(Mix.env()),
+      compilers: [:phoenix, :gettext] ++ Mix.compilers(),
+      start_permanent: false,
+      description: description(),
+      package: package(),
+      deps: deps()
+    ]
+  end
+
+  # Configuration for the OTP application.
+  #
+  # Type `mix help compile.app` for more information.
+  def application do
+    [
+      mod: {StripeMock.Application, []},
+      extra_applications: [:logger, :runtime_tools]
+    ]
+  end
+
+  defp description do
+    """
+    StripeMock is a Stripe mock server written with Elixir and Phoenix.
+    """
+  end
+
+  # Specifies which paths to compile per environment.
+  defp elixirc_paths(:test), do: ["lib", "test/support", "test/fixture"]
+  defp elixirc_paths(_), do: ["lib"]
+
+  defp package() do
+    [
+      name: :stripe_mock,
+      files: ["lib", "priv", "mix.exs", "README.md", "LICENSE"],
+      maintainers: ["Nick Kezhaya"],
+      licenses: ["MIT"],
+      links: %{"GitHub" => "https://github.com/whitepaperclip/stripe_mock"}
+    ]
+  end
+
+  # Specifies your project dependencies.
+  #
+  # Type `mix help deps` for examples and options.
+  defp deps do
+    [
+      {:phoenix, ">= 0.0.0"},
+      {:gettext, "~> 0.11"},
+      {:jason, "~> 1.0"},
+      {:plug_cowboy, "~> 2.0"},
+      {:ecto, "~> 3.1"},
+      {:ex_doc, ">= 0.0.0", only: :dev}
+    ]
+  end
+end
diff --git a/mix.lock b/mix.lock
new file mode 100644
index 0000000..10fc0e2
--- /dev/null
+++ b/mix.lock
@@ -0,0 +1,20 @@
+%{
+  "cowboy": {:hex, :cowboy, "2.6.3", "99aa50e94e685557cad82e704457336a453d4abcb77839ad22dbe71f311fcc06", [:rebar3], [{:cowlib, "~> 2.7.3", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.7.1", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm"},
+  "cowlib": {:hex, :cowlib, "2.7.3", "a7ffcd0917e6d50b4d5fb28e9e2085a0ceb3c97dea310505f7460ff5ed764ce9", [:rebar3], [], "hexpm"},
+  "decimal": {:hex, :decimal, "1.7.0", "30d6b52c88541f9a66637359ddf85016df9eb266170d53105f02e4a67e00c5aa", [:mix], [], "hexpm"},
+  "earmark": {:hex, :earmark, "1.3.2", "b840562ea3d67795ffbb5bd88940b1bed0ed9fa32834915125ea7d02e35888a5", [:mix], [], "hexpm"},
+  "ecto": {:hex, :ecto, "3.1.4", "69d852da7a9f04ede725855a35ede48d158ca11a404fe94f8b2fb3b2162cd3c9", [:mix], [{:decimal, "~> 1.6", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm"},
+  "ex_doc": {:hex, :ex_doc, "0.20.2", "1bd0dfb0304bade58beb77f20f21ee3558cc3c753743ae0ddbb0fd7ba2912331", [:mix], [{:earmark, "~> 1.3", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.10", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
+  "gettext": {:hex, :gettext, "0.16.1", "e2130b25eebcbe02bb343b119a07ae2c7e28bd4b146c4a154da2ffb2b3507af2", [:mix], [], "hexpm"},
+  "jason": {:hex, :jason, "1.1.2", "b03dedea67a99223a2eaf9f1264ce37154564de899fd3d8b9a21b1a6fd64afe7", [:mix], [{:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm"},
+  "makeup": {:hex, :makeup, "0.8.0", "9cf32aea71c7fe0a4b2e9246c2c4978f9070257e5c9ce6d4a28ec450a839b55f", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
+  "makeup_elixir": {:hex, :makeup_elixir, "0.13.0", "be7a477997dcac2e48a9d695ec730b2d22418292675c75aa2d34ba0909dcdeda", [:mix], [{:makeup, "~> 0.8", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm"},
+  "mime": {:hex, :mime, "1.3.1", "30ce04ab3175b6ad0bdce0035cba77bba68b813d523d1aac73d9781b4d193cf8", [:mix], [], "hexpm"},
+  "nimble_parsec": {:hex, :nimble_parsec, "0.5.0", "90e2eca3d0266e5c53f8fbe0079694740b9c91b6747f2b7e3c5d21966bba8300", [:mix], [], "hexpm"},
+  "phoenix": {:hex, :phoenix, "1.4.6", "8535f4a01291f0fbc2c30c78c4ca6a2eacc148db5178ad76e8b2fc976c590115", [:mix], [{:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 1.1", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 1.0 or ~> 2.0", [hex: :plug_cowboy, repo: "hexpm", optional: true]}], "hexpm"},
+  "phoenix_pubsub": {:hex, :phoenix_pubsub, "1.1.2", "496c303bdf1b2e98a9d26e89af5bba3ab487ba3a3735f74bf1f4064d2a845a3e", [:mix], [], "hexpm"},
+  "plug": {:hex, :plug, "1.8.0", "9d2685cb007fe5e28ed9ac27af2815bc262b7817a00929ac10f56f169f43b977", [:mix], [{:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: true]}], "hexpm"},
+  "plug_cowboy": {:hex, :plug_cowboy, "2.0.2", "6055f16868cc4882b24b6e1d63d2bada94fb4978413377a3b32ac16c18dffba2", [:mix], [{:cowboy, "~> 2.5", [hex: :cowboy, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
+  "plug_crypto": {:hex, :plug_crypto, "1.0.0", "18e49317d3fa343f24620ed22795ec29d4a5e602d52d1513ccea0b07d8ea7d4d", [:mix], [], "hexpm"},
+  "ranch": {:hex, :ranch, "1.7.1", "6b1fab51b49196860b733a49c07604465a47bdb78aa10c1c16a3d199f7f8c881", [:rebar3], [], "hexpm"},
+}
diff --git a/priv/gettext/en/LC_MESSAGES/errors.po b/priv/gettext/en/LC_MESSAGES/errors.po
new file mode 100644
index 0000000..cdec3a1
--- /dev/null
+++ b/priv/gettext/en/LC_MESSAGES/errors.po
@@ -0,0 +1,11 @@
+## `msgid`s in this file come from POT (.pot) files.
+##
+## Do not add, change, or remove `msgid`s manually here as
+## they're tied to the ones in the corresponding POT file
+## (with the same domain).
+##
+## Use `mix gettext.extract --merge` or `mix gettext.merge`
+## to merge POT files into PO files.
+msgid ""
+msgstr ""
+"Language: en\n"
diff --git a/priv/gettext/errors.pot b/priv/gettext/errors.pot
new file mode 100644
index 0000000..d6f47fa
--- /dev/null
+++ b/priv/gettext/errors.pot
@@ -0,0 +1,10 @@
+## This is a PO Template file.
+##
+## `msgid`s here are often extracted from source code.
+## Add new translations manually only if they're dynamic
+## translations that can't be statically extracted.
+##
+## Run `mix gettext.extract` to bring this file up to
+## date. Leave `msgstr`s empty as changing them here has no
+## effect: edit them in PO (`.po`) files instead.
+
diff --git a/test/fixture/card.ex b/test/fixture/card.ex
new file mode 100644
index 0000000..7e1aecc
--- /dev/null
+++ b/test/fixture/card.ex
@@ -0,0 +1,10 @@
+defmodule StripeMock.CardFixture do
+  def valid_card() do
+    %{
+      number: "4242424242424242",
+      exp_month: "12",
+      exp_year: "2020",
+      cvc: "123"
+    }
+  end
+end
diff --git a/test/stripe_mock_web/controllers/charge_controller_test.exs b/test/stripe_mock_web/controllers/charge_controller_test.exs
new file mode 100644
index 0000000..3dd9ff4
--- /dev/null
+++ b/test/stripe_mock_web/controllers/charge_controller_test.exs
@@ -0,0 +1,95 @@
+defmodule StripeMockWeb.ChargeControllerTest do
+  use StripeMockWeb.ConnCase
+  @moduletag :charge
+
+  alias StripeMock.API.Charge
+
+  setup :create_customer
+
+  describe "index" do
+    test "lists all charges", %{conn: conn} do
+      conn = get(conn, Routes.charge_path(conn, :index))
+      assert is_list(json_response(conn, 200)["data"])
+    end
+  end
+
+  describe "create charge" do
+    test "renders charge when data is valid", %{conn: conn, customer: customer} do
+      conn = post(conn, Routes.charge_path(conn, :create), create_attrs(customer.id))
+      assert %{"id" => id} = json_response(conn, 201)
+
+      conn = get(conn, Routes.charge_path(conn, :show, id))
+
+      assert %{
+               "id" => id,
+               "amount" => 5000,
+               "capture" => true,
+               "currency" => "some currency",
+               "customer" => "cus_" <> _,
+               "description" => "some description",
+               "metadata" => %{},
+               "statement_descriptor" => "some statement_descriptor",
+               "transfer_group" => "some transfer_group"
+             } = json_response(conn, 200)
+    end
+
+    test "renders errors when data is invalid", %{conn: conn} do
+      conn = post(conn, Routes.charge_path(conn, :create), invalid_attrs())
+      assert json_response(conn, 422)["errors"] != %{}
+    end
+  end
+
+  describe "update charge" do
+    setup [:create_charge]
+
+    test "renders charge when data is valid", %{conn: conn, charge: %Charge{id: id} = charge} do
+      conn = put(conn, Routes.charge_path(conn, :update, charge), update_attrs())
+      assert %{"id" => ^id} = json_response(conn, 200)
+
+      conn = get(conn, Routes.charge_path(conn, :show, id))
+
+      assert %{
+               "description" => "some updated description",
+               "metadata" => %{"key" => "val"}
+             } = json_response(conn, 200)
+    end
+
+    test "renders errors when data is invalid", %{conn: conn, charge: charge} do
+      conn = put(conn, Routes.charge_path(conn, :update, charge), invalid_attrs())
+      assert json_response(conn, 422)["errors"] != %{}
+    end
+  end
+
+  def create_attrs(customer_id) do
+    %{
+      amount: 5000,
+      capture: true,
+      currency: "some currency",
+      customer: customer_id,
+      description: "some description",
+      metadata: %{},
+      statement_descriptor: "some statement_descriptor",
+      transfer_group: "some transfer_group"
+    }
+  end
+
+  def update_attrs() do
+    %{
+      description: "some updated description",
+      metadata: %{"key" => "val"}
+    }
+  end
+
+  def invalid_attrs() do
+    %{
+      amount: nil,
+      capture: nil,
+      currency: nil,
+      customer: nil,
+      description: nil,
+      metadata: nil,
+      statement_descriptor: nil,
+      transfer_group: nil
+    }
+  end
+end
diff --git a/test/stripe_mock_web/controllers/customer_controller_test.exs b/test/stripe_mock_web/controllers/customer_controller_test.exs
new file mode 100644
index 0000000..f0c4f83
--- /dev/null
+++ b/test/stripe_mock_web/controllers/customer_controller_test.exs
@@ -0,0 +1,80 @@
+defmodule StripeMockWeb.CustomerControllerTest do
+  use StripeMockWeb.ConnCase
+  @moduletag :customer
+
+  alias StripeMock.API.Customer
+
+  @create_attrs %{
+    email: "foo@wat.com"
+  }
+  @update_attrs %{
+    name: "Bar"
+  }
+  @invalid_attrs %{
+    email: "not an email"
+  }
+
+  describe "index" do
+    setup :create_customer
+    setup :create_customer
+
+    test "lists all customers", %{conn: conn} do
+      conn = get(conn, Routes.customer_path(conn, :index))
+      refute json_response(conn, 200)["data"] == []
+    end
+  end
+
+  describe "create customer" do
+    test "renders customer when data is valid", %{conn: conn} do
+      conn = post(conn, Routes.customer_path(conn, :create), @create_attrs)
+      assert %{"id" => id} = json_response(conn, 201)
+
+      conn = get(conn, Routes.customer_path(conn, :show, id))
+
+      assert %{"id" => id} = json_response(conn, 200)
+    end
+
+    test "renders errors when data is invalid", %{conn: conn} do
+      conn = post(conn, Routes.customer_path(conn, :create), @invalid_attrs)
+      assert json_response(conn, 422)["errors"] != %{}
+    end
+  end
+
+  describe "update customer" do
+    setup [:create_customer]
+
+    test "renders customer when data is valid", %{
+      conn: conn,
+      customer: %Customer{id: id} = customer
+    } do
+      conn = put(conn, Routes.customer_path(conn, :update, customer), @update_attrs)
+      assert %{"id" => ^id} = json_response(conn, 200)
+
+      conn = get(conn, Routes.customer_path(conn, :show, id))
+
+      assert %{"id" => id} = json_response(conn, 200)
+    end
+
+    test "renders errors when data is invalid", %{conn: conn, customer: customer} do
+      conn = put(conn, Routes.customer_path(conn, :update, customer), @invalid_attrs)
+      assert json_response(conn, 422)["errors"] != %{}
+    end
+  end
+
+  describe "delete customer" do
+    setup [:create_customer]
+
+    test "deletes chosen customer", %{
+      conn: conn,
+      customer: %Customer{id: id} = customer
+    } do
+      conn = delete(conn, Routes.customer_path(conn, :delete, customer))
+      assert response(conn, 204)
+
+      assert %{"deleted" => true} =
+               conn
+               |> get(Routes.customer_path(conn, :show, id))
+               |> json_response(200)
+    end
+  end
+end
diff --git a/test/stripe_mock_web/controllers/refund_controller_test.exs b/test/stripe_mock_web/controllers/refund_controller_test.exs
new file mode 100644
index 0000000..52c975b
--- /dev/null
+++ b/test/stripe_mock_web/controllers/refund_controller_test.exs
@@ -0,0 +1,100 @@
+defmodule StripeMockWeb.RefundControllerTest do
+  use StripeMockWeb.ConnCase
+  @moduletag :refund
+
+  alias StripeMock.API.Refund
+
+  setup :create_customer
+  setup :create_charge
+
+  describe "index" do
+    test "lists all refunds", %{conn: conn} do
+      conn = get(conn, Routes.refund_path(conn, :index))
+      assert is_list(json_response(conn, 200)["data"])
+    end
+  end
+
+  describe "create refund" do
+    test "renders refund when data is valid", %{conn: conn, charge: charge} do
+      conn = post(conn, Routes.refund_path(conn, :create), create_attrs(charge.id))
+      assert %{"id" => id} = json_response(conn, 201)
+
+      conn = get(conn, Routes.refund_path(conn, :show, id))
+
+      assert %{
+               "id" => "re_" <> _,
+               "amount" => 5000,
+               "charge" => "ch_" <> _,
+               "metadata" => %{}
+             } = json_response(conn, 200)
+    end
+
+    test "amount defaults to full amount of the charge", %{conn: conn, charge: charge} do
+      params = %{create_attrs(charge.id) | amount: nil}
+      conn = post(conn, Routes.refund_path(conn, :create), params)
+      amount = charge.amount
+      assert %{"id" => id, "amount" => ^amount} = json_response(conn, 201)
+      refute is_nil(charge.amount)
+
+      conn = get(conn, Routes.refund_path(conn, :show, id))
+
+      assert %{
+               "id" => "re_" <> _,
+               "amount" => ^amount,
+               "charge" => "ch_" <> _,
+               "metadata" => %{}
+             } = json_response(conn, 200)
+    end
+
+    test "refunds limited to charge amount", %{conn: conn, charge: charge} do
+      params = %{create_attrs(charge.id) | amount: nil}
+
+      conn
+      |> post(Routes.refund_path(conn, :create), params)
+      |> json_response(:created)
+
+      params = %{create_attrs(charge.id) | amount: 1}
+      conn = post(conn, Routes.refund_path(conn, :create), params)
+      amount_errors = json_response(conn, 422)["errors"]["amount"]
+      assert is_list(amount_errors) and amount_errors != []
+    end
+
+    test "renders errors when data is invalid", %{conn: conn} do
+      conn = post(conn, Routes.refund_path(conn, :create), invalid_attrs())
+      assert json_response(conn, 422)["errors"] != %{}
+    end
+  end
+
+  describe "update refund" do
+    setup [:create_refund]
+
+    test "renders refund when data is valid", %{conn: conn, refund: %Refund{id: id} = refund} do
+      assert refund.metadata == %{}
+
+      conn = put(conn, Routes.refund_path(conn, :update, refund), %{metadata: %{"key" => "val"}})
+      assert %{"id" => ^id} = json_response(conn, 200)
+
+      conn = get(conn, Routes.refund_path(conn, :show, id))
+
+      assert %{"metadata" => %{"key" => "val"}} = json_response(conn, 200)
+    end
+  end
+
+  def create_attrs(charge_id) do
+    %{
+      amount: 5000,
+      charge: charge_id,
+      description: "some description",
+      metadata: %{}
+    }
+  end
+
+  def invalid_attrs() do
+    %{
+      amount: nil,
+      charge: nil,
+      description: nil,
+      metadata: nil
+    }
+  end
+end
diff --git a/test/stripe_mock_web/controllers/source_controller_test.exs b/test/stripe_mock_web/controllers/source_controller_test.exs
new file mode 100644
index 0000000..11c7496
--- /dev/null
+++ b/test/stripe_mock_web/controllers/source_controller_test.exs
@@ -0,0 +1,103 @@
+defmodule StripeMockWeb.SourceControllerTest do
+  use StripeMockWeb.ConnCase
+  @moduletag :source
+
+  alias StripeMock.API
+  alias StripeMock.API.Card
+  alias StripeMock.CardFixture
+
+  @card_attrs CardFixture.valid_card()
+  @update_attrs %{
+    name: "New Name",
+    address: "New Address"
+  }
+
+  setup :create_customer
+
+  describe "index" do
+    setup [:create_card]
+
+    test "lists all cards", %{conn: conn, customer: customer} do
+      conn = get(conn, Routes.customer_source_path(conn, :index, customer.id, object: "card"))
+      data = json_response(conn, 200)["data"]
+      assert is_list(data)
+
+      for source <- data do
+        assert source["customer"] == customer.id
+      end
+    end
+  end
+
+  describe "create card" do
+    test "renders card when data is valid", %{conn: conn, customer: customer} do
+      # Get a source token
+      %{"id" => token} =
+        conn
+        |> post(Routes.token_path(conn, :create), card: @card_attrs)
+        |> json_response(201)
+
+      %{"id" => id, "object" => "card"} =
+        conn
+        |> post(Routes.customer_source_path(conn, :create, customer.id), source: token)
+        |> json_response(201)
+
+      assert id =~ ~r/^card_/
+    end
+
+    test "renders errors when data is invalid", %{conn: conn, customer: customer} do
+      response =
+        conn
+        |> post(Routes.customer_source_path(conn, :create, customer.id), source: "non-token")
+        |> json_response(400)
+
+      assert is_map(response["error"])
+    end
+  end
+
+  describe "update card" do
+    setup [:create_card]
+
+    test "renders card when data is valid", %{conn: conn, card: %Card{id: id} = card} do
+      conn =
+        put(conn, Routes.customer_source_path(conn, :update, card.customer_id, card),
+          card: @update_attrs
+        )
+
+      assert %{"id" => ^id, "object" => "card"} = json_response(conn, 200)
+
+      conn = get(conn, Routes.customer_source_path(conn, :show, card.customer_id, card))
+
+      assert %{"id" => ^id, "object" => "card"} = json_response(conn, 200)
+    end
+  end
+
+  describe "delete card" do
+    setup [:create_card]
+
+    test "deletes chosen card", %{conn: conn, card: card} do
+      conn = delete(conn, Routes.customer_source_path(conn, :delete, card.customer_id, card))
+      assert response(conn, 200)
+
+      response =
+        conn
+        |> get(Routes.customer_source_path(conn, :show, card.customer_id, card))
+        |> json_response(200)
+
+      assert response["deleted"]
+    end
+  end
+
+  defp create_card(%{conn: conn, customer: customer}) do
+    %{"id" => token} =
+      conn
+      |> post(Routes.token_path(conn, :create), card: @card_attrs)
+      |> json_response(201)
+
+    %{"id" => id, "object" => "card"} =
+      conn
+      |> post(Routes.customer_source_path(conn, :create, customer.id), source: token)
+      |> json_response(201)
+
+    [card: API.get_card!(id)]
+  end
+end
diff --git a/test/stripe_mock_web/controllers/token_controller_test.exs b/test/stripe_mock_web/controllers/token_controller_test.exs
new file mode 100644
index 0000000..a38802a
--- /dev/null
+++ b/test/stripe_mock_web/controllers/token_controller_test.exs
@@ -0,0 +1,32 @@
+defmodule StripeMockWeb.TokenControllerTest do
+  use StripeMockWeb.ConnCase
+  @moduletag :token
+
+  @card_attrs StripeMock.CardFixture.valid_card()
+
+  describe "create token" do
+    test "accepts card data and sets type to card", %{conn: conn} do
+      conn = post(conn, Routes.token_path(conn, :create), card: @card_attrs)
+      assert %{"id" => id, "type" => "card"} = json_response(conn, 201)
+
+      conn = get(conn, Routes.token_path(conn, :show, id))
+
+      assert %{
+               "id" => "tok_" <> _,
+               "client_ip" => "127.0.0.1",
+               "created" => created,
+               "object" => "token",
+               "type" => "card",
+               "used" => false,
+               "card" => %{"id" => "card_" <> _}
+             } = json_response(conn, 200)
+
+      assert is_integer(created)
+    end
+
+    test "renders errors when data is invalid", %{conn: conn} do
+      conn = post(conn, Routes.token_path(conn, :create), %{})
+      assert json_response(conn, 422)["errors"] != %{}
+    end
+  end
+end
diff --git a/test/stripe_mock_web/plug/auth_test.exs b/test/stripe_mock_web/plug/auth_test.exs
new file mode 100644
index 0000000..6d8c2d6
--- /dev/null
+++ b/test/stripe_mock_web/plug/auth_test.exs
@@ -0,0 +1,51 @@
+defmodule StripeMockWeb.AuthTest do
+  use StripeMockWeb.ConnCase
+  @moduletag :auth
+
+  setup do
+    [conn: build_conn()]
+  end
+
+  test "bearer auth", %{conn: conn} do
+    conn
+    |> put_req_header("authorization", "bearer sk_test_123")
+    |> get(Routes.customer_path(conn, :index))
+    |> json_response(200)
+    |> assert
+  end
+
+  test "bearer fail", %{conn: conn} do
+    conn
+    |> put_req_header("authorization", "bearer foo")
+    |> get(Routes.customer_path(conn, :index))
+    |> json_response(401)
+    |> assert
+  end
+
+  test "basic auth", %{conn: conn} do
+    # sk_test_123:
+    conn
+    |> put_req_header("authorization", "basic c2tfdGVzdF8xMjM6")
+    |> get(Routes.customer_path(conn, :index))
+    |> json_response(200)
+    |> assert
+  end
+
+  test "basic auth pw", %{conn: conn} do
+    # sk_test_123:pw doesn't matter
+    conn
+    |> put_req_header("authorization", "basic c2tfdGVzdF8xMjM6cHcgZG9lc24ndCBtYXR0ZXI=")
+    |> get(Routes.customer_path(conn, :index))
+    |> json_response(200)
+    |> assert
+  end
+
+  test "basic fail", %{conn: conn} do
+    # foo
+    conn
+    |> put_req_header("authorization", "basic Zm9v")
+    |> get(Routes.customer_path(conn, :index))
+    |> json_response(401)
+    |> assert
+  end
+end
diff --git a/test/stripe_mock_web/views/error_view_test.exs b/test/stripe_mock_web/views/error_view_test.exs
new file mode 100644
index 0000000..c4a5558
--- /dev/null
+++ b/test/stripe_mock_web/views/error_view_test.exs
@@ -0,0 +1,15 @@
+defmodule StripeMockWeb.ErrorViewTest do
+  use StripeMockWeb.ConnCase, async: true
+
+  # Bring render/3 and render_to_string/3 for testing custom views
+  import Phoenix.View
+
+  test "renders 404.json" do
+    assert render(StripeMockWeb.ErrorView, "404.json", []) == %{errors: %{detail: "Not Found"}}
+  end
+
+  test "renders 500.json" do
+    assert render(StripeMockWeb.ErrorView, "500.json", []) ==
+             %{errors: %{detail: "Internal Server Error"}}
+  end
+end
diff --git a/test/support/conn_case.ex b/test/support/conn_case.ex
new file mode 100644
index 0000000..6906c9a
--- /dev/null
+++ b/test/support/conn_case.ex
@@ -0,0 +1,41 @@
+defmodule StripeMockWeb.ConnCase do
+  @moduledoc """
+  This module defines the test case to be used by
+  tests that require setting up a connection.
+
+  Such tests rely on `Phoenix.ConnTest` and also
+  import other functionality to make it easier
+  to build common data structures and query the data layer.
+
+  Finally, if the test case interacts with the database,
+  it cannot be async. For this reason, every test runs
+  inside a transaction which is reset at the beginning
+  of the test unless the test case is marked as async.
+  """
+
+  use ExUnit.CaseTemplate, async: false
+
+  using do
+    quote do
+      # Import conveniences for testing with connections
+      use Phoenix.ConnTest
+      import StripeMock.TestHelper
+      alias StripeMockWeb.Router.Helpers, as: Routes
+
+      # The default endpoint for testing
+      @endpoint StripeMockWeb.Endpoint
+    end
+  end
+
+  setup _tags do
+    {:ok, conn: Phoenix.ConnTest.build_conn()}
+  end
+
+  setup %{conn: conn} do
+    {:ok, conn: Plug.Conn.put_req_header(conn, "accept", "application/json")}
+  end
+
+  setup %{conn: conn} do
+    {:ok, conn: Plug.Conn.put_req_header(conn, "authorization", "bearer sk_test_123")}
+  end
+end
diff --git a/test/test_helper.exs b/test/test_helper.exs
new file mode 100644
index 0000000..08b5316
--- /dev/null
+++ b/test/test_helper.exs
@@ -0,0 +1,50 @@
+ExUnit.start()
+
+defmodule StripeMock.TestHelper do
+  alias StripeMock.API
+
+  @create_attrs %{
+    name: "Foo"
+  }
+
+  def create_customer() do
+    {:ok, customer} = API.create_customer(@create_attrs)
+    customer
+  end
+
+  def create_customer(_) do
+    [customer: create_customer()]
+  end
+
+  def create_charge(%{customer: customer}) do
+    [charge: create_charge(customer)]
+  end
+
+  def create_charge(%API.Customer{} = customer) do
+    {:ok, charge} =
+      API.create_charge(%{
+        amount: 5000,
+        capture: true,
+        currency: "some currency",
+        customer: customer.id,
+        description: "some description",
+        metadata: %{},
+        statement_descriptor: "some statement_descriptor",
+        transfer_group: "some transfer_group"
+      })
+
+    charge
+  end
+
+  def create_refund(%{charge: charge}) do
+    params = %{
+      amount: 5000,
+      charge_id: charge.id,
+      description: "some description",
+      metadata: %{}
+    }
+
+    {:ok, refund} = API.create_refund(params)
+    {:ok, refund: refund}
+  end
+end