Character Encoding Converter (UTF-8, EUC-KR, Shift_JIS, GBK…)

Old files and systems still use regional encodings — EUC-KR/CP949 in Korea, Shift_JIS and EUC-JP in Japan, GBK and Big5 for Chinese, Windows-1251 for Cyrillic — while the web and modern tools expect UTF-8. This converter reads files, hex bytes or typed text, detects the encoding (byte order marks, a strict UTF-8 check and the share of common characters in each East Asian encoding), and writes UTF-8, UTF-16 or any of the legacy encodings, listing characters the target cannot hold. It also pinpoints the first invalid byte in a file that should be UTF-8.

How to use this tool

1. Choose files, paste the bytes as hex, or type text to encode.
2. Leave the source on automatic detection, or pick it if you know it.
3. Choose the target encoding and whether to add a BOM.
4. Check the preview, then download the converted files.

Formula

Detection: BOM → ISO-2022-JP escapes → plain ASCII → strict UTF-8 → for EUC-KR, Shift_JIS, EUC-JP, GB18030 and Big5, the share of characters from each standard’s common block (e.g. EUC-KR lead bytes B0–C8 are the 2,350 everyday Hangul syllables).

Decoding uses the browser’s own WHATWG decoders. Legacy encoders are built by inverting those decoders over every byte pair and keeping the first code for each character, which is how the WHATWG encoders choose. UTF-8 validity follows Unicode Table 3-7.

Example

The hex bytes C7 D1 B1 B9 BE EE 20 C5 D8 BD BA C6 AE are detected as EUC-KR and read as 한국어 텍스트; converted to UTF-8 they become ED 95 9C EA B5 AD EC 96 B4 20 ED 85 8D EC 8A A4 ED 8A B8. Typing テスト with Shift_JIS as the target gives 83 65 83 58 83 67.