orjson

Fast, correct Python JSON library supporting dataclasses, datetimes, and numpy

orjson Copyleft license MPL-2.0 AND (Apache-2.0 OR MIT) Active ★ 8,200 v3.11.9 released 2026-05-06

Install

orjson on PyPI

pip

pip install orjson

uv

uv add orjson

poetry

poetry add orjson

Package facts

License	MPL-2.0 AND (Apache-2.0 OR MIT) (copyleft)
Python support	supports the current Python release (>=3.10)
Install friction	medium — platform-specific wheel
Runtime dependencies	none
Maintenance	actively maintained — 99 days since the last release
Last repo commit	2026-08-13
First released	2018-11-23
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: orjson-3.11.9-cp310-cp310-macosx_10_15_x86_64.macosx_11_0_arm64.macosx_10_15_universal2.whl; orjson-3.11.9-cp310-cp310-manylinux_2_17_aarch64.manylinux2014_aarch64.whl; orjson-3.11.9-cp310-cp310-manylinux_2_17_armv7l.manylinux2014_armv7l.whl; orjson-3.11.9-cp310-cp310-manylinux_2_17_i686.manylinux2014_i686.whl; orjson-3.11.9-cp310-cp310-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl; orjson-3.11.9-cp310-cp310-manylinux_2_17_s390x.manylinux2014_s390x.whl; orjson-3.11.9-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl; orjson-3.11.9-cp310-cp310-musllinux_1_2_aarch64.whl; orjson-3.11.9-cp310-cp310-musllinux_1_2_armv7l.whl; orjson-3.11.9-cp310-cp310-musllinux_1_2_i686.whl; orjson-3.11.9-cp310-cp310-musllinux_1_2_x86_64.whl; orjson-3.11.9-cp310-cp310-win32.whl; orjson-3.11.9-cp310-cp310-win_amd64.whl; orjson-3.11.9-cp311-cp311-macosx_10_15_x86_64.macosx_11_0_arm64.macosx_10_15_universal2.whl; orjson-3.11.9-cp311-cp311-macosx_15_0_arm64.whl; orjson-3.11.9-cp311-cp311-manylinux_2_17_aarch64.manylinux2014_aarch64.whl; orjson-3.11.9-cp311-cp311-manylinux_2_17_armv7l.manylinux2014_armv7l.whl; orjson-3.11.9-cp311-cp311-manylinux_2_17_i686.manylinux2014_i686.whl; orjson-3.11.9-cp311-cp311-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl; orjson-3.11.9-cp311-cp311-manylinux_2_17_s390x.manylinux2014_s390x.whl

Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: Apache Software LicenseLicense :: OSI Approved :: MIT LicenseLicense :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)Operating System :: MacOSOperating System :: Microsoft :: WindowsOperating System :: POSIX :: LinuxProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.15Programming Language :: Python :: Implementation :: CPythonProgramming Language :: RustTyping :: Typed

About orjson

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

orjson

orjson is a fast, correct JSON library for Python. It benchmarks as the fastest Python library for JSON and is more correct than the standard json library or other third-party libraries. It serializes dataclass, datetime, numpy, and UUID instances natively.

orjson.dumps() is something like 10x as fast as json, serializes common types and subtypes, has a default parameter for the caller to specify how to serialize arbitrary types, and has a number of flags controlling output.

orjson.loads() is something like 2x as fast as json, and is strictly compliant with UTF-8 and RFC 8259 ("The JavaScript Object Notation (JSON) Data Interchange Format").

Reading from and writing to files, line-delimited JSON files, and so on is not provided by the...

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