Msgpack — @coderbuzz/msgpack

High-performance MessagePack serialization for TypeScript.

Encodes and decodes JSON-compatible values to compact binary representation, optimized for minimal allocations and fast throughput.

Highlights

• Full MessagePack spec support: nil, bool, int, float, string, binary, array, map
• Reusable encoder buffer to minimize GC pressure
• Fast ASCII string path for short strings (common JSON keys)
• Compile-time branching for smallest integer representation
• Manual UTF-8 encoding for short strings, TextEncoder fallback for long ones
• encodeUnsafe zero-copy path for immediate consumption (e.g. writing to a socket)
• encodeInto for writing into a pre-allocated buffer
• encodedSize for pre-calculating byte length without allocating

Installation

# npm
npm install @coderbuzz/msgpack

# Bun
bun add @coderbuzz/msgpack

# Deno
import { encode, decode } from "npm:@coderbuzz/msgpack";

Usage

Encode & Decode

import { decode, encode } from "@coderbuzz/msgpack";

const bytes = encode({ name: "Alice", age: 30, active: true });
// => Uint8Array (compact binary)

const value = decode(bytes);
// => { name: 'Alice', age: 30, active: true }

Zero-Copy Encode

import { encodeUnsafe } from "@coderbuzz/msgpack";

// Returns a view into the internal buffer — NOT a copy.
// Must be consumed before the next encode() call.
const view = encodeUnsafe(payload);
socket.write(view);

Encode Into Pre-Allocated Buffer

import { encodeInto } from "@coderbuzz/msgpack";

const target = new Uint8Array(1024);
const bytesWritten = encodeInto(payload, target, 0);

Pre-Calculate Encoded Size

import { encodedSize } from "@coderbuzz/msgpack";

const size = encodedSize(payload);
const buf = new Uint8Array(size);
encodeInto(payload, buf);

Supported Types

| TypeScript type | MessagePack format | | -------------------- | ------------------------------------------------- | | null / undefined | nil (0xc0) | | boolean | true / false | | number (integer) | positive/negative fixint, uint8/16/32, int8/16/32 | | number (float) | float64 | | bigint | int64 / uint64 | | string | fixstr, str8, str16, str32 | | Uint8Array | bin8, bin16, bin32 | | Date | encoded as ISO string | | Array | fixarray, array16, array32 | | object | fixmap, map16, map32 |

API

// Encode a value, returning a new Uint8Array (caller owns memory)
function encode(value: unknown): Uint8Array;

// Encode a value, returning a view into the internal buffer (zero-copy)
// WARNING: invalidated by the next encode/encodeUnsafe call
function encodeUnsafe(value: unknown): Uint8Array;

// Encode a value into an existing buffer, returns bytes written
function encodeInto(
  value: unknown,
  target: Uint8Array,
  offset?: number,
): number;

// Decode a MessagePack buffer back to a value
function decode(data: Uint8Array): unknown;

// Calculate encoded byte size without allocating
function encodedSize(value: unknown): number;

License

MIT © 2026 Indra Gunawan