msgpack

MessagePack serializer

msgpack Permissive license Apache-2.0 Active ★ 2,100 v1.2.1 released 2026-06-18

Install

msgpack on PyPI

pip

pip install msgpack

uv

uv add msgpack

poetry

poetry add msgpack

Package facts

License	Apache-2.0 (permissive)
Python support	supports the current Python release (>=3.10)
Install friction	medium — platform-specific wheel
Runtime dependencies	none
Maintenance	actively maintained — 56 days since the last release
Last repo commit	2026-08-12
First released	2018-01-06
Popularity	one of the top 1,000 most-downloaded packages on PyPI (30-day window, as of 2026-08-13)
Known vulnerabilities	none known (OSV.dev, checked 2026-08-13)

Evidence: msgpack-1.2.1-cp310-cp310-macosx_10_9_x86_64.whl; msgpack-1.2.1-cp310-cp310-macosx_11_0_arm64.whl; msgpack-1.2.1-cp310-cp310-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl; msgpack-1.2.1-cp310-cp310-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl; msgpack-1.2.1-cp310-cp310-manylinux_2_31_riscv64.manylinux_2_39_riscv64.whl; msgpack-1.2.1-cp310-cp310-musllinux_1_2_aarch64.whl; msgpack-1.2.1-cp310-cp310-musllinux_1_2_riscv64.whl; msgpack-1.2.1-cp310-cp310-musllinux_1_2_x86_64.whl; msgpack-1.2.1-cp310-cp310-win32.whl; msgpack-1.2.1-cp310-cp310-win_amd64.whl; msgpack-1.2.1-cp311-cp311-macosx_10_9_x86_64.whl; msgpack-1.2.1-cp311-cp311-macosx_11_0_arm64.whl; msgpack-1.2.1-cp311-cp311-manylinux2014_aarch64.manylinux_2_17_aarch64.manylinux_2_28_aarch64.whl; msgpack-1.2.1-cp311-cp311-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl; msgpack-1.2.1-cp311-cp311-manylinux_2_31_riscv64.manylinux_2_39_riscv64.whl; msgpack-1.2.1-cp311-cp311-musllinux_1_2_aarch64.whl; msgpack-1.2.1-cp311-cp311-musllinux_1_2_riscv64.whl; msgpack-1.2.1-cp311-cp311-musllinux_1_2_x86_64.whl; msgpack-1.2.1-cp311-cp311-win32.whl; msgpack-1.2.1-cp311-cp311-win_amd64.whl

Keywords: msgpack, messagepack, serializer, serialization, binary

Development Status :: 5 - Production/StableIntended Audience :: DevelopersOperating System :: OS IndependentProgramming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: File Formats

About msgpack

from the package's own PyPI description — quoted content, verbatim

MessagePack for Python

Build Status (image) Documentation Status (image)

What is this?

MessagePack is an efficient binary serialization format. It lets you exchange data among multiple languages like JSON. But it's faster and smaller. This package provides CPython bindings for reading and writing MessagePack data.

Install

$ pip install msgpack

Pure Python implementation

The extension module in msgpack (msgpack._cmsgpack) does not support PyPy.

But msgpack provides a pure Python implementation (msgpack.fallback) for PyPy.

Windows

If you can't use a binary distribution, you need to install Visual Studio or the Windows SDK on Windows. Without the extension, the pure Python implementation on CPython runs slowly.

How to use

One-shot pack & unpack

Use packb for packing and unpackb for unpacking. msgpack provides dumps and loads...

Read as markdown · JSON record · Source repository · Homepage · Docs

AI interpretation — verify before relying

AI-generated interpretation of the package facts above; every digit, version, license, or vulnerability id it cites is grounded in the facts already shown on this page

msgpack is a fast binary serialization format that encodes Python objects into compact bytes and decodes them back, similar to JSON but smaller and quicker.

Medium install friction due to compiled C extensions for CPython (wheels provided for Python 3.10–3.11 across major platforms), though a pure Python fallback exists for PyPy. Active maintenance with a recent release 56 days ago.

Licensed under Apache-2.0 (permissive), allowing commercial and private use with minimal restrictions.

Usage

pip install msgpack
import msgpack
packed = msgpack.packb([1, 2, 3])
unpacked = msgpack.unpackb(packed)
print(unpacked)  # [1, 2, 3]

Requires Python 3.10 or later; on Windows without a binary wheel, Visual Studio or Windows SDK is needed to build the C extension.

Verdict: msgpack is a stable, actively maintained serialization library (2,100 GitHub stars, no known vulnerabilities) suitable for production use. The Apache-2.0 license poses no restrictions. Medium install friction is manageable given broad wheel coverage; the pure Python fallback ensures PyPy compatibility.

Needs verification

Performance comparison with json/pickle under typical workloads to validate 'faster and smaller' claim
Actual build time and complexity on Windows when binary wheels are unavailable
Whether the pure Python fallback performance is acceptable for production PyPy deployments

binary serialization formatmsgpack encoder decodercompact data serializationfast message packingjson alternative binarypython object serializationefficient data exchange