diff --git a/pumpkin-protocol/src/codec/bit_set.rs b/pumpkin-protocol/src/codec/bit_set.rs
new file mode 100644
index 00000000..27aa329d
--- /dev/null
+++ b/pumpkin-protocol/src/codec/bit_set.rs
@@ -0,0 +1,53 @@
+use std::num::NonZeroUsize;
+
+use bytes::{Buf, BufMut};
+use serde::{Serialize, Serializer};
+
+use crate::bytebuf::ByteBuf;
+use crate::bytebuf::ByteBufMut;
+
+use super::{var_int::VarInt, Codec, DecodeError};
+
+pub struct BitSet(pub VarInt, pub Vec<i64>);
+
+impl Codec<BitSet> for BitSet {
+    /// The maximum size of the BitSet is `remaining / 8`.
+    const MAX_SIZE: NonZeroUsize = unsafe { NonZeroUsize::new_unchecked(usize::MAX) };
+
+    fn written_size(&self) -> usize {
+        todo!()
+    }
+
+    fn encode(&self, write: &mut impl BufMut) {
+        write.put_var_int(&self.0);
+        for b in &self.1 {
+            write.put_i64(*b);
+        }
+    }
+
+    fn decode(read: &mut impl Buf) -> Result<Self, DecodeError> {
+        // read length
+        let length = read
+            .try_get_var_int()
+            .map_err(|_| DecodeError::Incomplete)?;
+        // vanilla uses remaining / 8
+        if length.0 as usize >= read.remaining() / 8 {
+            return Err(DecodeError::TooLarge);
+        }
+        let mut array: Vec<i64> = Vec::with_capacity(size_of::<i64>() * length.0 as usize);
+        for _ in 0..length.0 {
+            let long = read.try_get_i64().map_err(|_| DecodeError::Incomplete)?;
+            array.push(long);
+        }
+        Ok(BitSet(length, array))
+    }
+}
+
+impl Serialize for BitSet {
+    fn serialize<S>(&self, _serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        todo!()
+    }
+}
diff --git a/pumpkin-protocol/src/codec/identifier.rs b/pumpkin-protocol/src/codec/identifier.rs
new file mode 100644
index 00000000..6be5675c
--- /dev/null
+++ b/pumpkin-protocol/src/codec/identifier.rs
@@ -0,0 +1,101 @@
+use std::num::NonZeroUsize;
+
+use bytes::{Buf, BufMut};
+use serde::{de::Visitor, Deserialize, Deserializer, Serialize, Serializer};
+
+use crate::bytebuf::{ByteBuf, ByteBufMut};
+
+use super::{Codec, DecodeError};
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Identifier {
+    pub namespace: String,
+    pub path: String,
+}
+
+impl Identifier {
+    pub fn vanilla(path: &str) -> Self {
+        Self {
+            namespace: "minecraft".to_string(),
+            path: path.to_string(),
+        }
+    }
+}
+impl Codec<Self> for Identifier {
+    /// The maximum number of bytes a `Identifer` is the same as for a normal String.
+    const MAX_SIZE: NonZeroUsize = unsafe { NonZeroUsize::new_unchecked(i16::MAX as usize) };
+
+    fn written_size(&self) -> usize {
+        todo!()
+    }
+
+    fn encode(&self, write: &mut impl BufMut) {
+        write.put_string_len(&self.to_string(), Self::MAX_SIZE.get());
+    }
+
+    fn decode(read: &mut impl Buf) -> Result<Self, DecodeError> {
+        let identifer = read
+            .try_get_string_len(Self::MAX_SIZE.get())
+            .map_err(|_| DecodeError::Incomplete)?;
+        match identifer.split_once(":") {
+            Some((namespace, path)) => Ok(Identifier {
+                namespace: namespace.to_string(),
+                path: path.to_string(),
+            }),
+            None => Err(DecodeError::Incomplete),
+        }
+    }
+}
+
+impl Serialize for Identifier {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&self.to_string())
+    }
+}
+
+impl<'de> Deserialize<'de> for Identifier {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct IdentifierVisitor;
+
+        impl Visitor<'_> for IdentifierVisitor {
+            type Value = Identifier;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str("a valid Identifier (namespace:path)")
+            }
+
+            fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                self.visit_str(&v)
+            }
+
+            fn visit_str<E>(self, identifer: &str) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                match identifer.split_once(":") {
+                    Some((namespace, path)) => Ok(Identifier {
+                        namespace: namespace.to_string(),
+                        path: path.to_string(),
+                    }),
+                    None => Err(serde::de::Error::custom("Identifier can't be split")),
+                }
+            }
+        }
+        deserializer.deserialize_str(IdentifierVisitor)
+    }
+}
+
+impl std::fmt::Display for Identifier {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}:{}", self.namespace, self.path)
+    }
+}
diff --git a/pumpkin-protocol/src/codec/mod.rs b/pumpkin-protocol/src/codec/mod.rs
new file mode 100644
index 00000000..3af01e21
--- /dev/null
+++ b/pumpkin-protocol/src/codec/mod.rs
@@ -0,0 +1,27 @@
+use std::num::NonZeroUsize;
+
+use bytes::{Buf, BufMut};
+use thiserror::Error;
+
+pub mod bit_set;
+pub mod identifier;
+pub mod var_int;
+pub mod var_long;
+
+pub trait Codec<T> {
+    const MAX_SIZE: NonZeroUsize;
+
+    fn written_size(&self) -> usize;
+
+    fn encode(&self, write: &mut impl BufMut);
+
+    fn decode(read: &mut impl Buf) -> Result<T, DecodeError>;
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Debug, Error)]
+pub enum DecodeError {
+    #[error("Incomplete VarInt decode")]
+    Incomplete,
+    #[error("VarInt is too large")]
+    TooLarge,
+}
diff --git a/pumpkin-protocol/src/codec/var_int.rs b/pumpkin-protocol/src/codec/var_int.rs
new file mode 100644
index 00000000..4f502687
--- /dev/null
+++ b/pumpkin-protocol/src/codec/var_int.rs
@@ -0,0 +1,157 @@
+use std::{num::NonZeroUsize, ops::Deref};
+
+use super::{Codec, DecodeError};
+use bytes::{Buf, BufMut};
+use serde::{
+    de::{SeqAccess, Visitor},
+    Deserialize, Deserializer, Serialize, Serializer,
+};
+
+pub type VarIntType = i32;
+
+/**
+ * A variable-length integer type used by the Minecraft network protocol.
+ */
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct VarInt(pub VarIntType);
+
+impl Codec<Self> for VarInt {
+    /// The maximum number of bytes a `VarInt` can occupy.
+    const MAX_SIZE: NonZeroUsize = unsafe { NonZeroUsize::new_unchecked(5) };
+
+    /// Returns the exact number of bytes this varint will write when
+    /// [`Encode::encode`] is called, assuming no error occurs.
+    fn written_size(&self) -> usize {
+        match self.0 {
+            0 => 1,
+            n => (31 - n.leading_zeros() as usize) / 7 + 1,
+        }
+    }
+
+    fn encode(&self, write: &mut impl BufMut) {
+        let mut val = self.0;
+        for _ in 0..Self::MAX_SIZE.get() {
+            let b: u8 = val as u8 & 0b01111111;
+            val >>= 7;
+            write.put_u8(if val == 0 { b } else { b | 0b10000000 });
+            if val == 0 {
+                break;
+            }
+        }
+    }
+
+    fn decode(read: &mut impl Buf) -> Result<Self, DecodeError> {
+        let mut val = 0;
+        for i in 0..Self::MAX_SIZE.get() {
+            if !read.has_remaining() {
+                return Err(DecodeError::Incomplete);
+            }
+            let byte = read.get_u8();
+            val |= (i32::from(byte) & 0x7F) << (i * 7);
+            if byte & 0x80 == 0 {
+                return Ok(VarInt(val));
+            }
+        }
+        Err(DecodeError::TooLarge)
+    }
+}
+
+impl From<i32> for VarInt {
+    fn from(value: i32) -> Self {
+        VarInt(value)
+    }
+}
+
+impl From<u32> for VarInt {
+    fn from(value: u32) -> Self {
+        VarInt(value as i32)
+    }
+}
+
+impl From<u8> for VarInt {
+    fn from(value: u8) -> Self {
+        VarInt(value as i32)
+    }
+}
+
+impl From<usize> for VarInt {
+    fn from(value: usize) -> Self {
+        VarInt(value as i32)
+    }
+}
+
+impl From<VarInt> for i32 {
+    fn from(value: VarInt) -> Self {
+        value.0
+    }
+}
+
+impl AsRef<i32> for VarInt {
+    fn as_ref(&self) -> &i32 {
+        &self.0
+    }
+}
+
+impl Deref for VarInt {
+    type Target = i32;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl Serialize for VarInt {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut value = self.0 as u32;
+        let mut buf = Vec::new();
+
+        while value > 0x7F {
+            buf.put_u8(value as u8 | 0x80);
+            value >>= 7;
+        }
+
+        buf.put_u8(value as u8);
+
+        serializer.serialize_bytes(&buf)
+    }
+}
+
+impl<'de> Deserialize<'de> for VarInt {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct VarIntVisitor;
+
+        impl<'de> Visitor<'de> for VarIntVisitor {
+            type Value = VarInt;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str("a valid VarInt encoded in a byte sequence")
+            }
+
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+            where
+                A: SeqAccess<'de>,
+            {
+                let mut val = 0;
+                for i in 0..VarInt::MAX_SIZE.get() {
+                    if let Some(byte) = seq.next_element::<u8>()? {
+                        val |= (i32::from(byte) & 0b01111111) << (i * 7);
+                        if byte & 0b10000000 == 0 {
+                            return Ok(VarInt(val));
+                        }
+                    } else {
+                        break;
+                    }
+                }
+                Err(serde::de::Error::custom("VarInt was too large"))
+            }
+        }
+
+        deserializer.deserialize_seq(VarIntVisitor)
+    }
+}
diff --git a/pumpkin-protocol/src/codec/var_long.rs b/pumpkin-protocol/src/codec/var_long.rs
new file mode 100644
index 00000000..ceb2c1c9
--- /dev/null
+++ b/pumpkin-protocol/src/codec/var_long.rs
@@ -0,0 +1,158 @@
+use std::{num::NonZeroUsize, ops::Deref};
+
+use super::{Codec, DecodeError};
+use bytes::{Buf, BufMut};
+use serde::{
+    de::{self, SeqAccess, Visitor},
+    Deserialize, Deserializer, Serialize, Serializer,
+};
+
+pub type VarLongType = i64;
+
+/**
+ * A variable-length long type used by the Minecraft network protocol.
+ */
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct VarLong(pub VarLongType);
+
+impl Codec<Self> for VarLong {
+    /// The maximum number of bytes a `VarLong` can occupy.
+    const MAX_SIZE: NonZeroUsize = unsafe { NonZeroUsize::new_unchecked(10) };
+
+    /// Returns the exact number of bytes this varlong will write when
+    /// [`Encode::encode`] is called, assuming no error occurs.
+    fn written_size(&self) -> usize {
+        match self.0 {
+            0 => 1,
+            n => (31 - n.leading_zeros() as usize) / 7 + 1,
+        }
+    }
+
+    fn encode(&self, write: &mut impl BufMut) {
+        let mut x = self.0;
+        for _ in 0..Self::MAX_SIZE.get() {
+            let byte = (x & 0x7F) as u8;
+            x >>= 7;
+            if x == 0 {
+                write.put_slice(&[byte]);
+                break;
+            }
+            write.put_slice(&[byte | 0x80]);
+        }
+    }
+
+    fn decode(read: &mut impl Buf) -> Result<Self, DecodeError> {
+        let mut val = 0;
+        for i in 0..Self::MAX_SIZE.get() {
+            if !read.has_remaining() {
+                return Err(DecodeError::Incomplete);
+            }
+            let byte = read.get_u8();
+            val |= (i64::from(byte) & 0b01111111) << (i * 7);
+            if byte & 0b10000000 == 0 {
+                return Ok(VarLong(val));
+            }
+        }
+        Err(DecodeError::TooLarge)
+    }
+}
+
+impl From<i64> for VarLong {
+    fn from(value: i64) -> Self {
+        VarLong(value)
+    }
+}
+
+impl From<u32> for VarLong {
+    fn from(value: u32) -> Self {
+        VarLong(value as i64)
+    }
+}
+
+impl From<u8> for VarLong {
+    fn from(value: u8) -> Self {
+        VarLong(value as i64)
+    }
+}
+
+impl From<usize> for VarLong {
+    fn from(value: usize) -> Self {
+        VarLong(value as i64)
+    }
+}
+
+impl From<VarLong> for i64 {
+    fn from(value: VarLong) -> Self {
+        value.0
+    }
+}
+
+impl AsRef<i64> for VarLong {
+    fn as_ref(&self) -> &i64 {
+        &self.0
+    }
+}
+
+impl Deref for VarLong {
+    type Target = i64;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl Serialize for VarLong {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut value = self.0 as u64;
+        let mut buf = Vec::new();
+
+        while value > 0x7F {
+            buf.put_u8(value as u8 | 0x80);
+            value >>= 7;
+        }
+
+        buf.put_u8(value as u8);
+
+        serializer.serialize_bytes(&buf)
+    }
+}
+
+impl<'de> Deserialize<'de> for VarLong {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct VarLongVisitor;
+
+        impl<'de> Visitor<'de> for VarLongVisitor {
+            type Value = VarLong;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str("a valid VarInt encoded in a byte sequence")
+            }
+
+            fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
+            where
+                A: SeqAccess<'de>,
+            {
+                let mut val = 0;
+                for i in 0..VarLong::MAX_SIZE.get() {
+                    if let Some(byte) = seq.next_element::<u8>()? {
+                        val |= (i64::from(byte) & 0b01111111) << (i * 7);
+                        if byte & 0b10000000 == 0 {
+                            return Ok(VarLong(val));
+                        }
+                    } else {
+                        break;
+                    }
+                }
+                Err(de::Error::custom("VarInt was too large"))
+            }
+        }
+
+        deserializer.deserialize_seq(VarLongVisitor)
+    }
+}