Other answers here seem to indicate that constructing this list programmatically is difficult and fraught with traps. However, doing so is probably unnecessary since the documentation contains a complete list of the standard encodings Python supports, and has done since Python 2.3.
You can find these lists (for each stable version of the language so far released) at:
Below are the lists for each documented version of Python. Note that if you want backwards-compatibility rather than just supporting a particular version of Python, you can just copy the list from the latest Python version and check whether each encoding exists in the Python running your program before trying to use it.
Python 2.3 (59 encodings)
['ascii',
'cp037',
'cp424',
'cp437',
'cp500',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp869',
'cp874',
'cp875',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8']
Python 2.4 (85 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8']
Python 2.5 (86 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 2.6 (90 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 2.7 (93 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp720',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp858',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_11',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.0 (89 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.1 (90 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.2 (92 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp720',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp858',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.3 (93 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp424',
'cp437',
'cp500',
'cp720',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp858',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'cp65001',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.4 (96 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp273',
'cp424',
'cp437',
'cp500',
'cp720',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp858',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1125',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'cp65001',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_11',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_u',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.5 (98 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp273',
'cp424',
'cp437',
'cp500',
'cp720',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp858',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1125',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'cp65001',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_11',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_t',
'koi8_u',
'kz1048',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.6 (98 encodings)
Same as previous version.
Python 3.7 (98 encodings)
Same as previous version.
Python 3.8 (97 encodings)
['ascii',
'big5',
'big5hkscs',
'cp037',
'cp273',
'cp424',
'cp437',
'cp500',
'cp720',
'cp737',
'cp775',
'cp850',
'cp852',
'cp855',
'cp856',
'cp857',
'cp858',
'cp860',
'cp861',
'cp862',
'cp863',
'cp864',
'cp865',
'cp866',
'cp869',
'cp874',
'cp875',
'cp932',
'cp949',
'cp950',
'cp1006',
'cp1026',
'cp1125',
'cp1140',
'cp1250',
'cp1251',
'cp1252',
'cp1253',
'cp1254',
'cp1255',
'cp1256',
'cp1257',
'cp1258',
'euc_jp',
'euc_jis_2004',
'euc_jisx0213',
'euc_kr',
'gb2312',
'gbk',
'gb18030',
'hz',
'iso2022_jp',
'iso2022_jp_1',
'iso2022_jp_2',
'iso2022_jp_2004',
'iso2022_jp_3',
'iso2022_jp_ext',
'iso2022_kr',
'latin_1',
'iso8859_2',
'iso8859_3',
'iso8859_4',
'iso8859_5',
'iso8859_6',
'iso8859_7',
'iso8859_8',
'iso8859_9',
'iso8859_10',
'iso8859_11',
'iso8859_13',
'iso8859_14',
'iso8859_15',
'iso8859_16',
'johab',
'koi8_r',
'koi8_t',
'koi8_u',
'kz1048',
'mac_cyrillic',
'mac_greek',
'mac_iceland',
'mac_latin2',
'mac_roman',
'mac_turkish',
'ptcp154',
'shift_jis',
'shift_jis_2004',
'shift_jisx0213',
'utf_32',
'utf_32_be',
'utf_32_le',
'utf_16',
'utf_16_be',
'utf_16_le',
'utf_7',
'utf_8',
'utf_8_sig']
Python 3.9 (97 encodings)
Same as previous version.
Python 3.10 (97 encodings)
Same as previous version.
Python 3.11 (97 encodings)
Same as previous version.
In case they're relevant to anyone's use case, note that the docs also list some Python-specific encodings, many of which seem to be primarily for use by Python's internals or are otherwise weird in some way, like the 'undefined'
encoding which always throws an exception if you try to use it. You probably want to ignore these completely if, like the question-asker here, you're trying to figure out what encoding was used for some text you've come across in the real world. As of Python 3.7, the list is as follows:
["idna",
"mbcs",
"oem",
"palmos",
"punycode",
"raw_unicode_escape",
"rot_13",
"undefined",
"unicode_escape",
"unicode_internal",
"base64_codec",
"bz2_codec",
"hex_codec",
"quopri_codec",
"uu_codec",
"zlib_codec"]
Some older Python versions had a string_escape
special encoding that I've not included in the above list because it's been removed from the language.
Finally, in case you'd like to update my tables above for a newer version of Python, here's the (crude, not very robust) script I used to generate them:
import re
import requests
import lxml.html
import pprint
previous = None
for version, url in [
('2.3', 'https://docs.python.org/2.3/lib/node130.html'),
('2.4', 'https://docs.python.org/2.4/lib/standard-encodings.html'),
('2.5', 'https://docs.python.org/2.5/lib/standard-encodings.html'),
('2.6', 'https://docs.python.org/2.6/library/codecs.html#standard-encodings'),
('2.7', 'https://docs.python.org/2.7/library/codecs.html#standard-encodings'),
('3.0', 'https://docs.python.org/3.0/library/codecs.html#standard-encodings'),
('3.1', 'https://docs.python.org/3.1/library/codecs.html#standard-encodings'),
('3.2', 'https://docs.python.org/3.2/library/codecs.html#standard-encodings'),
('3.3', 'https://docs.python.org/3.3/library/codecs.html#standard-encodings'),
('3.4', 'https://docs.python.org/3.4/library/codecs.html#standard-encodings'),
('3.5', 'https://docs.python.org/3.5/library/codecs.html#standard-encodings'),
('3.6', 'https://docs.python.org/3.6/library/codecs.html#standard-encodings'),
('3.7', 'https://docs.python.org/3.7/library/codecs.html#standard-encodings'),
('3.8', 'https://docs.python.org/3.8/library/codecs.html#standard-encodings'),
('3.9', 'https://docs.python.org/3.9/library/codecs.html#standard-encodings'),
('3.10', 'https://docs.python.org/3.10/library/codecs.html#standard-encodings'),
('3.11', 'https://docs.python.org/3.11/library/codecs.html#standard-encodings'),
]:
html = requests.get(url).text
# Work-around for weird HTML markup in recent versions of Python documentation:
html = re.sub('<[/]?p>', '', html)
doc = lxml.html.fromstring(html)
standard_encodings_table = doc.xpath(
'//table[preceding::h2[.//text()[contains(., "Standard Encodings")]]][//th/text()="Codec"]'
)[0]
codecs = standard_encodings_table.xpath('.//td[1]/text()')
print("## Python %s (%i encodings)\n" % (version, len(codecs)))
if codecs == previous:
print('_Same as previous version._\n')
else:
print('```python\n' + pprint.pformat(codecs) + '\n```\n')
previous = codecs