json5

A Python implementation of the JSON5 data format.

json5 Permissive license Files: Everything except for the benchmarks/*.json files. Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1.… (full text in the JSON record) Active ★ 283 v0.15.0 released 2026-06-19

Install

json5 on PyPI

pip

pip install json5

uv

uv add json5

poetry

poetry add json5

Package facts

License	Files: Everything except for the benchmarks/*.json files. Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1.… (full text in the JSON record) (permissive)
Python support	supports the current Python release (>=3.8.0)
Install friction	low — pure-Python wheel
Runtime dependencies	none
Maintenance	actively maintained — 55 days since the last release
Last repo commit	2026-06-24
First released	2015-03-26
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: json5-0.15.0-py3-none-any.whl

Keywords: json5

Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: Apache Software LicenseProgramming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9

About json5

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

pyjson5

A Python implementation of the JSON5 data format.

JSON5 extends the JSON data interchange format to make it slightly more usable as a configuration language:

JavaScript-style comments (both single and multi-line) are legal.
Object keys may be unquoted if they are legal ECMAScript identifiers
Objects and arrays may end with trailing commas.
Strings can be single-quoted, and multi-line string literals are allowed.

There are a few other more minor extensions to JSON; see the above page for the full details.

This project implements a reader and writer implementation for Python; where possible, it mirrors the standard Python JSON API package for ease of use.

There is one notable difference from the JSON api: the load() and loads() methods support optionally checking for (and rejecting) duplicate object keys; pass allow_duplicate_keys=False to do so (duplicates are allowed by default).

This is an early release. It has been reasonably well-tested, but it is SLOW. It can be 1000-6000x slower than the C-optimized JSON module, and is 200x slower (or more) than...

Read as markdown · JSON record · Source repository

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

Parses and serializes JSON5, a relaxed JSON format that allows comments, unquoted keys, trailing commas, and single-quoted strings for use as a configuration language.

Installs cleanly with no runtime dependencies. Actively maintained with a recent release (55 days ago) and steady repository activity. Supports Python 3.8–3.14.

Licensed under Apache License 2.0 (permissive), allowing commercial and derivative use with attribution. Benchmark files use MIT licenses; no restrictions on production use.

Usage

import json5

data = json5.loads('{key: "value", // comment\n}')
print(data)

json5.dumps(data, indent=2)

Performance caveat: the implementation is 200–6000× slower than the standard json module; unsuitable for high-throughput parsing.

Verdict: A well-maintained, permissively licensed JSON5 implementation suitable for parsing relaxed JSON in configuration workflows. Zero dependencies and broad Python version support make it easy to integrate. However, its documented performance limitation (200–6000× slower than json) means it should be reserved for configuration files and non-performance-critical use cases.

Needs verification

Whether the performance penalty is acceptable for your configuration file sizes and parsing frequency.
Whether the `allow_duplicate_keys` parameter and other API extensions meet your validation requirements.

json5 parserjson5 serializerjson with commentsconfiguration file formatrelaxed json parsingjavascript-style jsonjson5 reader writer