Get a list of all the encodings Python can encode to

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:

https://docs.python.org/2.3/lib/node130.html
https://docs.python.org/2.4/lib/standard-encodings.html
https://docs.python.org/2.5/lib/standard-encodings.html
https://docs.python.org/2.6/library/codecs.html#standard-encodings
https://docs.python.org/2.7/library/codecs.html#standard-encodings
https://docs.python.org/3.0/library/codecs.html#standard-encodings
https://docs.python.org/3.1/library/codecs.html#standard-encodings
https://docs.python.org/3.2/library/codecs.html#standard-encodings
https://docs.python.org/3.3/library/codecs.html#standard-encodings
https://docs.python.org/3.4/library/codecs.html#standard-encodings
https://docs.python.org/3.5/library/codecs.html#standard-encodings
https://docs.python.org/3.6/library/codecs.html#standard-encodings
https://docs.python.org/3.7/library/codecs.html#standard-encodings

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)

['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 3.7 (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']

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 requests
import lxml.html
import pprint

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'),
]:
    html = requests.get(url).text
    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)" % (version, len(codecs)))
    print('<pre><code>' + pprint.pformat(codecs) + '</code></pre>')

Unfortunately encodings.aliases.aliases.keys() is NOT an appropriate answer.

aliases(as one would/should expect) contains several cases where different keys are mapped to the same value e.g. 1252 and windows_1252 are both mapped to cp1252. You could save time if instead of aliases.keys() you use set(aliases.values()).

BUT THERE'S A WORSE PROBLEM: aliases doesn't contain codecs that don't have aliases (like cp856, cp874, cp875, cp737, and koi8_u).

>>> from encodings.aliases import aliases
>>> def find(q):
...     return [(k,v) for k, v in aliases.items() if q in k or q in v]
...
>>> find('1252') # multiple aliases
[('1252', 'cp1252'), ('windows_1252', 'cp1252')]
>>> find('856') # no codepage 856 in aliases
[]
>>> find('koi8') # no koi8_u in aliases
[('cskoi8r', 'koi8_r')]
>>> 'x'.decode('cp856') # but cp856 is a valid codec
u'x'
>>> 'x'.decode('koi8_u') # but koi8_u is a valid codec
u'x'
>>>

It's also worth noting that however you obtain a full list of codecs, it may be a good idea to ignore the codecs that aren't about encoding/decoding character sets, but do some other transformation e.g. zlib, quopri, and base64.

Which brings us to the question of WHY you want to "try encoding bytes into many different encodings". If we know that, we may be able to steer you in the right direction.

For a start, that's ambiguous. One DEcodes bytes into unicode, and one ENcodes unicode into bytes. Which do you want to do?

What are you really trying to achieve: Are you trying to determine which codec to use to decode some incoming bytes, and plan to attempt this with all possible codecs? [note: latin1 will decode anything] Are you trying to determine the language of some unicode text by trying to encode it with all possible codecs? [note: utf8 will encode anything].

Maybe you should try using the Universal Encoding Detector (chardet) library instead of implementing it yourself.

>>> import chardet
>>> s = '\xe2\x98\x83' # ☃
>>> chardet.detect(s)
{'confidence': 0.505, 'encoding': 'utf-8'}