---
id: ujson
version: "5.13.0"
license: BSD-3-Clause AND TCL
license_treatment: permissive
maintenance: active
---

# ujson — Ultra fast JSON encoder and decoder for Python

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

## Install

pip install ujson
uv add ujson
poetry add ujson

## Description

# UltraJSON

[![PyPI version](https://img.shields.io/pypi/v/ujson.svg?logo=pypi&logoColor=FFE873)](https://pypi.org/project/ujson)
[![Supported Python versions](https://img.shields.io/pypi/pyversions/ujson.svg?logo=python&logoColor=FFE873)](https://pypi.org/project/ujson)
[![PyPI downloads](https://img.shields.io/pypi/dm/ujson.svg)](https://pypistats.org/packages/ujson)
[![GitHub Actions status](https://github.com/ultrajson/ultrajson/workflows/Test/badge.svg)](https://github.com/ultrajson/ultrajson/actions)
[![codecov](https://codecov.io/gh/ultrajson/ultrajson/branch/main/graph/badge.svg)](https://codecov.io/gh/ultrajson/ultrajson)
[![DOI](https://zenodo.org/badge/1418941.svg)](https://zenodo.org/badge/latestdoi/1418941)
[![Code style: Black](https://img.shields.io/badge/code%20style-Black-000000.svg)](https://github.com/psf/black)

UltraJSON is an ultra fast JSON encoder and decoder written in pure C with bindings for
Python.

Install with pip:

```sh
python -m pip install ujson
```

## Project status

> [!WARNING]
> UltraJSON's architecture is fundamentally ill-suited to making changes without
> risk of introducing new security vulnerabilities. As a result, this library
> has...

## AI interpretation — verify before relying

Ultra-fast JSON encoder and decoder written in C with Python bindings, offering a drop-in replacement for standard JSON libraries with optional HTML escaping, ASCII enforcement, and pretty-printing.

Verdict: Actively maintained, production-stable JSON library with no known vulnerabilities and strong platform coverage. Maintenance-only status and explicit recommendation to migrate to orjson for new projects signal architectural limitations, but it remains a solid choice for existing codebases requiring fast JSON processing without introducing new dependencies.

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