Changelog

7.1.0 (2026-03-11)

Features:

  • Added PEP 263 encoding declaration detection — # -*- coding: ... -*- and # coding=... declarations on lines 1–2 of Python source files are now recognized with confidence 0.95 (#249)

  • Added chardet.universaldetector backward-compatibility stub so that from chardet.universaldetector import UniversalDetector works with a deprecation warning (#341)

Fixes:

  • Fixed false UTF-7 detection of ASCII text containing ++ or +word patterns (#332)

  • Fixed 0.5s startup cost on first detect() call — model norms are now computed during loading instead of lazily iterating 21M entries (#333)

  • Fixed undocumented encoding name changes between chardet 5.x and 7.0 — detect() now returns chardet 5.x-compatible names by default (#338)

  • Improved ISO-2022-JP family detection — recognizes ESC sequences for ISO-2022-JP-2004 (JIS X 0213) and ISO-2022-JP-EXT (JIS X 0201 Kana)

  • Fixed silent truncation of corrupt model data (iter_unpack yielded fewer tuples instead of raising)

  • Fixed incorrect date in LICENSE

Performance:

  • 5.5x faster first-detect time (~0.42s → ~0.075s) by computing model norms as a side-product of load_models()

  • ~40% faster model parsing via struct.iter_unpack for bulk entry extraction (eliminates ~305K individual unpack calls)

New API parameters:

  • Added compat_names parameter (default True) to detect(), detect_all(), and UniversalDetector — set to False to get raw Python codec names instead of chardet 5.x/6.x compatible display names

  • Added prefer_superset parameter (default False) — remaps legacy ISO/subset encodings to their modern Windows/CP superset equivalents (e.g., ASCII → Windows-1252, ISO-8859-1 → Windows-1252). This will default to ``True`` in the next major version (8.0).

  • Deprecated should_rename_legacy in favor of prefer_superset — a deprecation warning is emitted when used

Improvements:

  • Switched internal canonical encoding names to Python codec names (e.g., "utf-8" instead of "UTF-8"), with compat_names controlling the public output format. See Usage for the full mapping table.

  • Added lookup_encoding() to registry for case-insensitive resolution of arbitrary encoding name input to canonical names

  • Achieved 100% line coverage across all source modules (+31 tests)

  • Updated benchmark numbers: 98.2% encoding accuracy, 95.2% language accuracy on 2,510 test files

  • Pinned test-data cloning to chardet release version tags for reproducible builds

7.0.1 (2026-03-04)

Fixes:

  • Fixed false UTF-7 detection of SHA-1 git hashes (#324)

  • Fixed _SINGLE_LANG_MAP missing aliases for single-language encoding lookup (e.g., big5 → big5hkscs)

  • Fixed PyPy TypeError in UTF-7 codec handling

Improvements:

  • Retrained bigram models — 24 previously failing test cases now pass

  • Updated language equivalences for mutual intelligibility (Slovak/Czech, East Slavic + Bulgarian, Malay/Indonesian, Scandinavian languages)

7.0.0 (2026-03-02)

Ground-up, MIT-licensed rewrite of chardet. Same package name, same public API — drop-in replacement for chardet 5.x/6.x.

Highlights:

  • MIT license (previous versions were LGPL)

  • 96.8% accuracy on 2,179 test files (+2.3pp vs chardet 6.0.0, +7.7pp vs charset-normalizer)

  • 41x faster than chardet 6.0.0 with mypyc (28x pure Python), 7.5x faster than charset-normalizer

  • Language detection for every result (90.5% accuracy across 49 languages)

  • 99 encodings across six eras (MODERN_WEB, LEGACY_ISO, LEGACY_MAC, LEGACY_REGIONAL, DOS, MAINFRAME)

  • 12-stage detection pipeline — BOM, UTF-16/32 patterns, escape sequences, binary detection, markup charset, ASCII, UTF-8 validation, byte validity, CJK gating, structural probing, statistical scoring, post-processing

  • Bigram frequency models trained on CulturaX multilingual corpus data for all supported language/encoding pairs

  • Optional mypyc compilation — 1.49x additional speedup on CPython

  • Thread-safe detect() and detect_all() with no measurable overhead; scales on free-threaded Python 3.13t+

  • Negligible import memory (96 B)

  • Zero runtime dependencies

Breaking changes vs 6.0.0:

  • detect() and detect_all() now default to encoding_era=EncodingEra.ALL (6.0.0 defaulted to MODERN_WEB)

  • Internal architecture is completely different (probers replaced by pipeline stages). Only the public API is preserved.

  • LanguageFilter is accepted but ignored (deprecation warning emitted)

  • chunk_size is accepted but ignored (deprecation warning emitted)

6.0.0 (2026-02-22)

Features:

  • Unified single-byte charset detection with proper language-specific bigram models for all single-byte encodings (replaces Latin1Prober and MacRomanProber heuristics)

  • 38 new languages: Arabic, Belarusian, Breton, Croatian, Czech, Danish, Dutch, English, Esperanto, Estonian, Farsi, Finnish, French, German, Icelandic, Indonesian, Irish, Italian, Kazakh, Latvian, Lithuanian, Macedonian, Malay, Maltese, Norwegian, Polish, Portuguese, Romanian, Scottish Gaelic, Serbian, Slovak, Slovene, Spanish, Swedish, Tajik, Ukrainian, Vietnamese, Welsh

  • EncodingEra filtering via new encoding_era parameter

  • max_bytes and chunk_size parameters for detect(), detect_all(), and UniversalDetector

  • -e/--encoding-era CLI flag

  • EBCDIC detection (CP037, CP500)

  • Direct GB18030 support (replaces redundant GB2312 prober)

  • Binary file detection

  • Python 3.12, 3.13, and 3.14 support

Breaking changes:

  • Dropped Python 3.7, 3.8, and 3.9 (requires Python 3.10+)

  • Removed Latin1Prober and MacRomanProber

  • Removed EUC-TW support

  • Removed LanguageFilter.NONE

  • detect() default changed to encoding_era=EncodingEra.MODERN_WEB

Fixes:

  • Fixed CP949 state machine

  • Fixed SJIS distribution analysis (second-byte range >= 0x80)

  • Fixed UTF-16/32 detection for non-ASCII-heavy text

  • Fixed GB18030 char_len_table

  • Fixed UTF-8 state machine

  • Fixed detect_all() returning inactive probers

  • Fixed early cutoff bug

5.2.0 (2023-08-01)

  • Added support for running the CLI via python -m chardet

5.1.0 (2022-12-01)

  • Added should_rename_legacy argument to remap legacy encoding names to modern equivalents

  • Added MacRoman encoding prober

  • Added --minimal flag to chardetect CLI

  • Added type annotations and mypy CI

  • Added support for Python 3.11

  • Removed support for Python 3.6

5.0.0 (2022-06-25)

  • Added Johab Korean prober

  • Added UTF-16/32 BE/LE probers

  • Added test data for Croatian, Czech, Hungarian, Polish, Slovak, Slovene, Greek, Turkish

  • Improved XML tag filtering

  • Made detect_all return child prober confidences

  • Dropped Python 2.7, 3.4, 3.5 (requires Python 3.6+)

4.0.0 (2020-12-10)

  • Added detect_all() function returning all candidate encodings

  • Converted single-byte charset probers to nested dicts (performance)

  • CharsetGroupProber now short-circuits on definite matches (performance)

  • Added language field to detect_all output

  • Dropped Python 2.6, 3.4, 3.5

3.0.4 (2017-06-08)

  • Fixed packaging issue with pytest_runner

  • Updated old URLs in README and docs

3.0.3 (2017-05-16)

  • Fixed crash when debug logging was enabled

3.0.2 (2017-04-12)

  • Fixed detect sometimes returning None instead of a result dict

3.0.1 (2017-04-11)

  • Fixed crash in EUC-TW prober with certain strings

3.0.0 (2017-04-11)

  • Added Turkish ISO-8859-9 detection

  • Modernized naming conventions (typical_positive_ratio instead of mTypicalPositiveRatio)

  • Added language property to probers and results

  • Switched from Travis to GitHub Actions

  • Fixed CharsetGroupProber.state not being set to FOUND_IT

2.3.0 (2014-10-07)

  • Added CP932 detection

  • Fixed UTF-8 BOM not detected as UTF-8-SIG

  • Switched chardetect to use argparse

2.2.1 (2013-12-18)

  • Fixed missing parenthesis in chardetect.py

2.2.0 (2013-12-16)

  • First release after merger with charade (Python 3 support)

2.1.1 (2012-10-01)

  • Bumped version past Mark Pilgrim’s last release

  • chardetect can now read from stdin (Erik Rose)

  • Fixed BOM byte strings for UCS-4-2143 and UCS-4-3412 (Toshio Kuratomi)

  • Restored Mark Pilgrim’s original docs and COPYING file (Toshio Kuratomi)

1.1 (2012-07-27)

  • Added chardetect CLI tool (Erik Rose)

  • Fixed utf8prober crash when character is out of range (David Cramer)

  • Cleaned up detection logic to fail gracefully (David Cramer)

  • Fixed feed encoding errors (David Cramer)

1.0.1 (2008-04-19)

  • Packaging fix, added egg distributions for Python 2.4 and 2.5 (Mark Pilgrim)

1.0 (2006-12-23)

  • Initial release: Python 2 port of Mozilla’s universal charset detector (Mark Pilgrim)