diff --git a/Project.toml b/Project.toml
index 29f243580..d550cbed3 100644
--- a/Project.toml
+++ b/Project.toml
@@ -13,7 +13,7 @@ Compose = "a81c6b42-2e10-5240-aca2-a61377ecd94b"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 GATlab = "f0ffcf3b-d13a-433e-917c-cc44ccf5ead2"
 GeneralizedGenerated = "6b9d7cbe-bcb9-11e9-073f-15a7a543e2eb"
-JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
+JSON3 = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
 LightXML = "9c8b4983-aa76-5018-a973-4c85ecc9e179"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"
@@ -58,7 +58,7 @@ GATlab = "0.1"
 GeneralizedGenerated = "0.2, 0.3"
 Graphs = "1"
 Graphviz_jll = "2"
-JSON = "0.20, 0.21"
+JSON3 = "1"
 LightXML = "0.8, 0.9"
 LinearAlgebra = "1.9"
 Logging = "1.9"
diff --git a/docs/Project.toml b/docs/Project.toml
index c6bedb1e7..d5094855d 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -6,7 +6,7 @@ Convex = "f65535da-76fb-5f13-bab9-19810c17039a"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 GATlab = "f0ffcf3b-d13a-433e-917c-cc44ccf5ead2"
-JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
+JSON3 = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
 JSONSchema = "7d188eb4-7ad8-530c-ae41-71a32a6d4692"
 LaTeXStrings = "b964fa9f-0449-5b57-a5c2-d3ea65f4040f"
 Literate = "98b081ad-f1c9-55d3-8b20-4c87d4299306"
diff --git a/docs/literate/graphics/graphviz_wiring_diagrams.jl b/docs/literate/graphics/graphviz_wiring_diagrams.jl
index 6801db77a..5a37867b4 100644
--- a/docs/literate/graphics/graphviz_wiring_diagrams.jl
+++ b/docs/literate/graphics/graphviz_wiring_diagrams.jl
@@ -170,6 +170,6 @@ Graphviz.pprint(graph)
 # Catlab provides a simple wrapper around the Graphviz command-line programs.
 # For example, here is the JSON output for the graph.
 
-import JSON
+import JSON3
 
-JSON.parse(Graphviz.run_graphviz(graph, format="json0"))
+JSON3.read(Graphviz.run_graphviz(graph, format="json0"))
diff --git a/src/graphics/GraphvizWiringDiagrams.jl b/src/graphics/GraphvizWiringDiagrams.jl
index d8c868bc3..1cb1fd817 100644
--- a/src/graphics/GraphvizWiringDiagrams.jl
+++ b/src/graphics/GraphvizWiringDiagrams.jl
@@ -5,7 +5,7 @@ This module requires Graphviz v2.42 or higher.
 module GraphvizWiringDiagrams
 export graphviz_layout, to_graphviz, to_graphviz_property_graph
 
-import JSON
+import JSON3
 using LinearAlgebra: normalize
 using MLStyle: @match
 using StaticArrays
@@ -530,7 +530,7 @@ the wires are ignored.
 """
 function graphviz_layout(diagram::WiringDiagram; kw...)
   graph = to_graphviz(diagram; kw...)
-  doc = JSON.parse(Graphviz.run_graphviz(graph, format="json0"))
+  doc = JSON3.read(Graphviz.run_graphviz(graph, format="json0"))
   graphviz_layout(diagram, parse_graphviz(doc))
 end
 
diff --git a/src/wiring_diagrams/GraphML.jl b/src/wiring_diagrams/GraphML.jl
index 513943e28..2f862b0b4 100644
--- a/src/wiring_diagrams/GraphML.jl
+++ b/src/wiring_diagrams/GraphML.jl
@@ -18,7 +18,7 @@ export read_graphml, parse_graphml, write_graphml, generate_graphml,
   convert_from_graphml_data, convert_to_graphml_data
 
 using DataStructures: OrderedDict
-import JSON
+import JSON3
 using LightXML
 
 using ...Graphs
@@ -191,8 +191,8 @@ generate_graphml_data_type(::Type{Vector{T}}) where T = "json"
 generate_graphml_data_value(x::Number) = string(x)
 generate_graphml_data_value(x::String) = x
 generate_graphml_data_value(x::Symbol) = string(x)
-generate_graphml_data_value(x::Dict) = JSON.json(x)
-generate_graphml_data_value(x::Vector) = JSON.json(x)
+generate_graphml_data_value(x::Dict) = JSON3.write(x)
+generate_graphml_data_value(x::Vector) = JSON3.write(x)
 
 convert_to_graphml_data(x) = convert_to_graph_data(x)
 
@@ -351,7 +351,7 @@ parse_graphml_data_value(::Type{Val{:long}}, s::String) = parse(Int, s)
 parse_graphml_data_value(::Type{Val{:float}}, s::String) = parse(Float32, s)
 parse_graphml_data_value(::Type{Val{:double}}, s::String) = parse(Float64, s)
 parse_graphml_data_value(::Type{Val{:string}}, s::String) = s
-parse_graphml_data_value(::Type{Val{:json}}, s::String) = JSON.parse(s)
+parse_graphml_data_value(::Type{Val{:json}}, s::String) = JSON3.read(s)
 
 convert_from_graphml_data(T::Type, data) = convert_from_graph_data(T, data)
 
diff --git a/src/wiring_diagrams/JSON.jl b/src/wiring_diagrams/JSON.jl
index f8d22937b..a5deece29 100644
--- a/src/wiring_diagrams/JSON.jl
+++ b/src/wiring_diagrams/JSON.jl
@@ -19,7 +19,7 @@ export read_json_graph, parse_json_graph, write_json_graph, generate_json_graph,
   convert_from_json_graph_data, convert_to_json_graph_data
 
 using DataStructures: OrderedDict
-import JSON
+import JSON3
 
 using ..DirectedWiringDiagrams, ..WiringDiagramSerialization
 
@@ -33,8 +33,13 @@ const PortData = NamedTuple{(:kind,:port),Tuple{PortKind,Int}}
 """
 function write_json_graph(diagram::WiringDiagram, filename::String;
                           indent::Union{Int,Nothing}=nothing)
+  data = generate_json_graph(diagram)
   open(filename, "w") do io
-    JSON.print(io, generate_json_graph(diagram), indent)
+    if isnothing(indent)
+      JSON3.write(io, data)
+    else
+      JSON3.pretty(io, data, JSON3.AlignmentContext(indent=indent))
+    end
   end
 end
 
@@ -108,14 +113,15 @@ convert_to_json_graph_data(x) = convert_to_graph_data(x)
 """
 function read_json_graph(
     BoxValue::Type, PortValue::Type, WireValue::Type, filename::String)
-  parse_json_graph(BoxValue, PortValue, WireValue, JSON.parsefile(filename))
+  json_string = read(filename, String)
+  parse_json_graph(BoxValue, PortValue, WireValue, JSON3.read(json_string))
 end
 
 """ Parse a wiring diagram from a JSON string or dict.
 """
 function parse_json_graph(
     BoxValue::Type, PortValue::Type, WireValue::Type, s::Union{AbstractString,IO})
-  parse_json_graph(BoxValue, PortValue, WireValue, JSON.parse(s))
+  parse_json_graph(BoxValue, PortValue, WireValue, JSON3.read(s))
 end
 function parse_json_graph(
     ::Type{BoxValue}, ::Type{PortValue}, ::Type{WireValue},
diff --git a/test/Project.toml b/test/Project.toml
index 0a1303586..fd0223c50 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -8,7 +8,7 @@ DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 GATlab = "f0ffcf3b-d13a-433e-917c-cc44ccf5ead2"
 Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
 IterativeSolvers = "42fd0dbc-a981-5370-80f2-aaf504508153"
-JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
+JSON3 = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
 LightXML = "9c8b4983-aa76-5018-a973-4c85ecc9e179"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MetaGraphs = "626554b9-1ddb-594c-aa3c-2596fe9399a5"
diff --git a/test/graphics/GraphvizGraphs.jl b/test/graphics/GraphvizGraphs.jl
index 50b3f4c44..109668193 100644
--- a/test/graphics/GraphvizGraphs.jl
+++ b/test/graphics/GraphvizGraphs.jl
@@ -1,6 +1,6 @@
 module TestGraphvizGraphs
 using Test
-import JSON
+import JSON3
 
 using Catlab.Theories, Catlab.Graphs, Catlab.Graphics.GraphvizGraphs
 import Catlab.Graphics: Graphviz
@@ -19,14 +19,14 @@ const stmts = Graphviz.filter_statements
 data_path(name::String) = joinpath(@__DIR__, "data", name)
 
 # Undirected simple graph.
-doc = open(JSON.parse, data_path("graphviz_graph.json"), "r")
+doc = open(JSON3.read, data_path("graphviz_graph.json"), "r")
 parsed = parse_graphviz(doc)
 @test parsed isa SymmetricPropertyGraph
 @test nv(parsed) == 10
 @test ne(parsed) ÷ 2 == 13
 
 # Directed simple graph
-doc = open(JSON.parse, data_path("graphviz_digraph.json"), "r")
+doc = open(JSON3.read, data_path("graphviz_digraph.json"), "r")
 parsed = parse_graphviz(doc)
 @test parsed isa PropertyGraph
 @test nv(parsed) == 5
diff --git a/test/graphics/GraphvizWiringDiagrams.jl b/test/graphics/GraphvizWiringDiagrams.jl
index 996bb8665..d224f7e29 100644
--- a/test/graphics/GraphvizWiringDiagrams.jl
+++ b/test/graphics/GraphvizWiringDiagrams.jl
@@ -1,7 +1,7 @@
 module TestGraphvizWiringDiagrams
 
 using Test
-import JSON
+import JSON3
 
 using Catlab.Theories, Catlab.WiringDiagrams, Catlab.Graphics
 using Catlab.CategoricalAlgebra: @acset
@@ -101,7 +101,7 @@ graph = to_graphviz(d, box_labels=true, junction_labels=true, port_labels=true)
 #################
 
 diagram = include(joinpath("data", "graphviz_wiring_diagram.jl"))
-doc = open(JSON.parse,
+doc = open(JSON3.read,
   joinpath(@__DIR__, "data", "graphviz_wiring_diagram.json"), "r")
 graph = parse_graphviz(doc)
 layout = graphviz_layout(diagram, graph)
diff --git a/test/wiring_diagrams/JSON.jl b/test/wiring_diagrams/JSON.jl
index 98925b6d4..46eea11a8 100644
--- a/test/wiring_diagrams/JSON.jl
+++ b/test/wiring_diagrams/JSON.jl
@@ -1,34 +1,33 @@
 module TestJSONWiringDiagrams
 using Test
 
-import JSON
 using Catlab.Theories, Catlab.WiringDiagrams
 
-# Round trip wiring diagrams with dictionary box and wire data.
-
-function roundtrip(f::WiringDiagram)
-  json = sprint(JSON.print, generate_json_graph(f), 2)
-  parse_json_graph(Dict, Nothing, Dict, JSON.parse(json))
+function roundtrip(BoxT, PortT, WireT, f::WiringDiagram)
+  mktempdir() do dir
+    path = joinpath(dir, "dwd.json")
+    write_json_graph(f, path, indent=2)
+    read_json_graph(BoxT, PortT, WireT, path)
+  end
 end
 
+# Round trip wiring diagrams with dictionary box and wire data.
+
 ports(n) = Nothing[ nothing for i in 1:n ]
 diagram = WiringDiagram(ports(1), ports(1))
-f = Box(Dict("name" => "f", "type" => "foo"), ports(1), ports(1))
+f = Box(Dict(:name => "f", :type => "foo"), ports(1), ports(1))
 fv = add_box!(diagram, f)
 add_wires!(diagram, [
-  Wire(Dict("name" => "w1", "type" => "woo"),
+  Wire(Dict(:name => "w1", :type => "woo"),
       (input_id(diagram), 1) => (fv, 1)),
-  Wire(Dict("name" => "w2", "type" => "woo"),
+  Wire(Dict(:name => "w2", :type => "woo"),
        (fv, 1) => (output_id(diagram), 1)),
 ])
-@test roundtrip(diagram) == diagram
+@test roundtrip(Dict, Nothing, Dict, diagram) == diagram
 
 # Round trip wiring diagrams with symbolic box and port values.
 
-function roundtrip_symbolic(f::WiringDiagram)
-  json = sprint(JSON.print, generate_json_graph(f), 2)
-  parse_json_graph(Symbol, Symbol, Nothing, JSON.parse(json))
-end
+roundtrip_symbolic(f::WiringDiagram) = roundtrip(Symbol, Symbol, Nothing, f)
 
 f = singleton_diagram(Box(:f, [:A], [:B]))
 g = singleton_diagram(Box(:g, [:B], [:C]))