There is no way to get what you want.

Ask your clients to upload using a specified charset only.

If you see the single byte 0xC4, that could be a latin-1 encoded Ä, though in ISO-8859-5 (kyrillic) it would be as valid as with latin-1 though encoding a different character, the Ф.

Therefore it is impossible to detect the encoding without knowing the content in advance.

What you describe from the other languages, is usually a very dumb heuristic.

1. Check if the input is valid UTF-8/16/32 by corresponding validators, perhaps even helped by a BOM
2. If not, fall back to a single byte encoding derived from the hosts local settings

nimble_csv supports converting data to utf-8 before parsing / converting from utf-8 before dumping. By default it even ships NimbleCSV.Spreadsheet, which uses utf-16 le to work with excel csv’s. But you’ll need to setup a module per encoding.

The libMagic route is definitely worth considering. I have a library for that. Low profile, but working.

https://github.com/evadne/gen_magic