chardet

chardet guesses the encoding of text files.

Detects...

ASCII, UTF-8, UTF-16 (2 variants), UTF-32 (4 variants)
Big5, GB2312, EUC-TW, HZ-GB-2312, ISO-2022-CN (Traditional and Simplified Chinese)
EUC-JP, SHIFT_JIS, CP932, ISO-2022-JP (Japanese)
EUC-KR, ISO-2022-KR (Korean)
KOI8-R, MacCyrillic, IBM855, IBM866, ISO-8859-5, windows-1251 (Cyrillic)
ISO-8859-2, windows-1250 (Hungarian)
ISO-8859-5, windows-1251 (Bulgarian)
windows-1252 (English)
ISO-8859-7, windows-1253 (Greek)
ISO-8859-8, windows-1255 (Visual and Logical Hebrew)
TIS-620 (Thai)

Requires Python 2.1 or later.

Command-line Tool

chardet comes with a command-line script which reports on the encodings of one or more files:

% chardetect.py somefile someotherfile
somefile: windows-1252 with confidence 0.5
someotherfile: ascii with confidence 1.0