---
id: simplejson
version: "4.1.1"
license: MIT OR AFL-2.1
license_treatment: permissive
maintenance: active
---

# simplejson — Simple, fast, extensible JSON encoder/decoder for Python

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

## Install

pip install simplejson
uv add simplejson
poetry add simplejson

## Description

simplejson
----------

simplejson is a simple, fast, complete, correct and extensible
JSON <http://json.org> encoder and decoder for Python 3.8+
with legacy support for Python 2.7.  It is pure Python code
with no dependencies, but includes an optional C extension
for a serious speed boost.

The latest documentation for simplejson can be read online here:
https://simplejson.readthedocs.io/

simplejson is the externally maintained development version of the
json library included with Python (since 2.6). This version is tested
with Python 3.14 (including free-threaded builds) and maintains
backwards compatibility with Python 3.8+. A legacy Python 2.7 wheel
is also published.

The encoder can be specialized to provide serialization in any kind of
situation, without any special support by the objects to be serialized
(somewhat like pickle). This is best done with the ``default`` kwarg
to dumps.

The decoder can handle incoming JSON strings of any specified encoding
(UTF-8 by default). It can also be specialized to post-process JSON
objects with the ``object_hook`` or ``object_pairs_hook`` kwargs. This
is particularly useful for implementing protocols such as JSON-RPC
that have a...

## AI interpretation — verify before relying

simplejson is a fast, complete JSON encoder and decoder for Python 3.8+ (with Python 2.7 legacy support) that offers specialized serialization and deserialization hooks, plus an optional C extension for performance.

Verdict: simplejson is a mature, actively maintained JSON library with zero known vulnerabilities, no dependencies, and broad Python version support. Its permissive dual license and low install friction make it a reliable choice for projects needing JSON serialization with customization hooks or performance optimization via its optional C extension.

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