---
id: ormsgpack
version: "1.12.2"
license: Apache-2.0 OR MIT
license_treatment: permissive
maintenance: active
---

# ormsgpack — Fast, correct Python msgpack library supporting dataclasses, datetimes, and numpy

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install ormsgpack
uv add ormsgpack
poetry add ormsgpack

## Description

# ormsgpack

![PyPI - Version](https://img.shields.io/pypi/v/ormsgpack)
![PyPI - Python Version](https://img.shields.io/pypi/pyversions/ormsgpack)
![PyPI - Downloads](https://img.shields.io/pypi/dm/ormsgpack)

ormsgpack is a fast [MessagePack](https://msgpack.org/) serialization library for Python
derived from [orjson](https://github.com/ijl/orjson), with native support for various
Python types.

ormsgpack follows semantic versioning and supports CPython, PyPy and GraalPy.

Links:

- [Repository](https://github.com/ormsgpack/ormsgpack)
- [Documentation](https://ormsgpack.readthedocs.io/)

## Installation

pip

```sh
pip install ormsgpack
```

uv

```sh
uv add ormsgpack
```

Installing from a source distribution requires
[Rust](https://www.rust-lang.org/) 1.81 or newer and
[maturin](https://github.com/PyO3/maturin).

## Quickstart

This is an example of serializing and deserializing an object:

```python
>>> import ormsgpack, datetime, numpy
>>> event = {
...     "type": "put",
...     "time": datetime.datetime(1970, 1, 1),
...     "uid": 1,
...     "data": numpy.array([1, 2]),
... }
>>> ormsgpack.packb(event,...

## AI interpretation — verify before relying

ormsgpack is a fast MessagePack serialization library for Python with native support for dataclasses, datetimes, and numpy arrays, derived from orjson.

Verdict: ormsgpack is a production-ready, actively maintained serialization library with broad platform coverage and no security issues. Medium install friction is offset by pre-built wheels for all major Python versions and platforms, making it suitable for performance-critical applications needing fast MessagePack encoding with rich type support.

[View on SkillFed](https://skillfed.io/packages/ormsgpack) · [View on PyPI](https://pypi.org/project/ormsgpack/)