Base64URL Decoder
Turn URL-safe Base64 back into text: - and _ are mapped to + and /, missing = padding is restored, and the bytes are decoded as UTF-8. Useful for reading the payload of a JWT or an encoded parameter in a link. Characters outside the Base64 alphabet are reported as an error.
How to use
- Paste a Base64URL string that uses - and _.
- The tool maps - and _ back to + and / and restores the missing padding.
- The result is decoded as UTF-8; a JWT payload will usually look like JSON.
FAQ
What if the output is garbled?
The original data may not be UTF-8 text, or it may be binary. This tool decodes text only; use a command-line tool for binary data.
Does it decode standard Base64?
Yes, strings using + and / are handled too.
Why can I read a JWT payload directly?
JWTs are signed, not encrypted by default, so the payload is readable Base64URL. Do not put secrets in it.
Further reading