charset_normalizer

Changed

• Raised upper bound of setuptools to v84 (#794)
• Cache performance access optimization for our CharInfo struct (prebuilt only).

Fixed

• No longer decoding large content when the noise detector output give a high entropy. Only impacted large content input >1M bytes.

3.5.0 (2026-08-12)

Added

• Explicit support for Python 3.15

Fixed

• Comparing a CharsetMatch to a non-alias encoding strings (#773)
• Return 0.0 CharsetMatch.multi_byte_usage for empty payloads instead of crashing (#774)
• A file with both a charset declaration and BOM/SIG did not verify first the BOM/SIG charset.
• iso2022* cases misdetected due to a flaw in our multibyte chunking logic.

Changed

• Replaced the optional mypyc build with Cython extensions while retaining the pure Python fallback. The previous engine (mypyc) started to hit rough limit around the optimization of our noise/coherence detector while Cython allows us to steer the engine toward the right generated optimized sources. This change SHOULD not impact bundler (e.g. Pyinstaller) as the module are immediately discoverable (i.e. not hidden import like mypyc did). Moreover, a long wished distribution is the abi3 wheels, this will allow us to no longer rush each year when a new Python interpreter is released. We still distribute the interpreter specific wheels for faster performance.
• Applied micro-optimization on several utils.
• CharsetMatches no longer sort on each match insertion.

Misc

• Removed an old performance optimization attempt in apy.py (success_fast_tracked+payload_result_cache).

Fixed

• Regression in our fallback path leading to a decode error. (#771) We've yanked 3.4.8 as a result of that bug.

3.4.8 (2026-07-06)

Fixed

• Wall import time due to cascade codec imports for our multibyte first sort of iana supported codecs (#742)
• Unnecessary json import at runtime (#753)
• Inverse capitalization not seen by noise detector (#731)

Changed

• No longer holding a global cache for our noise / coherence measurements. Relax RSS memory usage.
• Micro-optimizations in our noise / coherence measurements.
• No longer using regex search by default for our preemptive charset mark algorithm.
• Raised upperbound of setuptools to v83.
• Raised upperbound of mypy(c) to v2.1.

Removed

• Redundant UTF7 BOM marker (#730)

Changed

• Pre-built optimized version using mypy[c] v1.20.
• Relax setuptools constraint to setuptools>=68,<82.1.

Fixed

• Correctly remove SIG remnant in utf-7 decoded string. (#718) (#716)

3.4.6 (2026-03-15)

Changed

• Flattened the logic in charset_normalizer.md for higher performance. Removed eligible(..) and feed(...) in favor of feed_info(...).
• Raised upper bound for mypy[c] to 1.20, for our optimized version.
• Updated UNICODE_RANGES_COMBINED using Unicode blocks v17.

Fixed

• Edge case where noise difference between two candidates can be almost insignificant. (#672)
• CLI --normalize writing to wrong path when passing multiple files in. (#702)

Misc

• Freethreaded pre-built wheels now shipped in PyPI starting with 3.14t. (#616)

3.4.5 (2026-03-06)

Changed

• Update setuptools constraint to setuptools>=68,<=82.
• Raised upper bound of mypyc for the optional pre-built extension to v1.19.1

Fixed

• Add explicit link to lib math in our optimized build. (#692)
• Logger level not restored correctly for empty byte sequences. (#701)
• TypeError when passing bytearray to from_bytes. (#703)

Misc

• Applied safe micro-optimizations in both our noise detector and language detector.
• Rewrote the query_yes_no function (inside CLI) to avoid using ambiguous licensed code.
• Added cd.py submodule into mypyc optional compilation to reduce further the performance impact.

[!WARNING]
mypyc changed the usual binary output for the optimized wheel. Beware, especially if using PyInstaller or alike. See https://github.com/jawah/charset_normalizer/issues/714

3.4.4 (2025-10-13)

Changed

• Bound setuptools to a specific constraint setuptools>=68,<=81.
• Raised upper bound of mypyc for the optional pre-built extension to v1.18.2

Removed

• setuptools-scm as a build dependency.

Misc

• Enforced hashes in dev-requirements.txt and created ci-requirements.txt for security purposes.
• Additional pre-built wheels for riscv64, s390x, and armv7l architectures.
• Restore multiple.intoto.jsonl in GitHub releases in addition to individual attestation file per wheel.

3.4.3 (2025-08-09)

Changed

• mypy(c) is no longer a required dependency at build time if CHARSET_NORMALIZER_USE_MYPYC isn't set to 1. (#595) (#583)
• automatically lower confidence on small bytes samples that are not Unicode in detect output legacy function. (#391)

Added

• Custom build backend to overcome inability to mark mypy as an optional dependency in the build phase.
• Support for Python 3.14

Fixed

• sdist archive contained useless directories.
• automatically fallback on valid UTF-16 or UTF-32 even if the md says it's noisy. (#633)

Misc

• SBOM are automatically published to the relevant GitHub release to comply with regulatory changes. Each published wheel comes with its SBOM. We choose CycloneDX as the format.
• Prebuilt optimized wheel are no longer distributed by default for CPython 3.7 due to a change in cibuildwheel.

3.4.2 (2025-05-02)

Fixed

• Addressed the DeprecationWarning in our CLI regarding argparse.FileType by backporting the target class into the package. (#591)
• Improved the overall reliability of the detector with CJK Ideographs. (#605) (#587)

Changed

• Optional mypyc compilation upgraded to version 1.15 for Python >= 3.9

🚀 We're still raising awareness around HTTP/2, and HTTP/3!

Did you know that Internet Explorer 11 shipped with an optional HTTP/2 support back in 2013? also libcurl did ship it in 2014[...] Using Requests today is the rough equivalent of using EOL Windows 8! We promptly invite Python developers to look at the first drop-in replacement for Requests, namely Niquests. Ship with native WebSocket, SSE, Happy Eyeballs, DNS over HTTPS, and so on[...] All of this while remaining compatible with all Requests prior plug-ins / add-ons.

It leverages charset-normalizer in a better way! Check it out, you will gain up to being 3X faster and get a real/respectable support with it.

3.4.1 (2024-12-24)

Changed

• Project metadata are now stored using pyproject.toml instead of setup.cfg using setuptools as the build backend.
• Enforce annotation delayed loading for a simpler and consistent types in the project.
• Optional mypyc compilation upgraded to version 1.14 for Python >= 3.8

Added

• pre-commit configuration.
• noxfile.

Removed

• build-requirements.txt as per using pyproject.toml native build configuration.
• bin/integration.py and bin/serve.py in favor of downstream integration test (see noxfile).
• setup.cfg in favor of pyproject.toml metadata configuration.
• Unused utils.range_scan function.

Fixed

• Converting content to Unicode bytes may insert utf_8 instead of preferred utf-8. (#572)
• Deprecation warning "'count' is passed as positional argument" when converting to Unicode bytes on Python 3.13+

🚀 charset-normalizer is raising awareness around HTTP/2, and HTTP/3!

Did you know that Internet Explorer 11 shipped with an optional HTTP/2 support back in 2013? also libcurl did ship it in 2014[...] All of this while our community is still struggling to make a firm advancement in HTTP clients. Now, many of you use Requests as the defacto http client, now, and for many years now, Requests has been frozen. Being left in a vegetative state and not evolving, this blocked millions of developers from using more advanced features.

We promptly invite Python developers to look at the drop-in replacement for Requests, namely Niquests. It leverage charset-normalizer in a better way! Check it out, you will be positively surprised! Don't wait another decade.

We are thankful to @microsoft and involved parties for funding our work through the Microsoft FOSS Fund program.

3.4.0 (2024-10-08)

Added

• Argument --no-preemptive in the CLI to prevent the detector to search for hints.
• Support for Python 3.13 (#512)

Fixed

• Relax the TypeError exception thrown when trying to compare a CharsetMatch with anything else than a CharsetMatch.
• Improved the general reliability of the detector based on user feedbacks. (#520) (#509) (#498) (#407) (#537)
• Declared charset in content (preemptive detection) not changed when converting to utf-8 bytes. (#381)