Base64URL Encoder And Decoder
Encode UTF-8 text as Base64URL, or decode Base64URL text back into standard text.
What is Base64URL?
Base64URL is the URL and filename safe Base64 alphabet from RFC 4648. It uses A-Z, a-z, 0-9, hyphen, and underscore instead of the standard Base64 + and / characters, so encoded text can fit more safely in URL tokens, filenames, and compact identifiers.
This tool encodes UTF-8 text bytes to Base64URL and decodes padded or unpadded Base64URL back to readable UTF-8 text. Encoding defaults to unpadded output because that is common for URL tokens, but you can include = padding when another system expects canonical padded groups.
The decoder rejects characters outside the Base64URL alphabet, invalid padding, and decoded bytes that are not valid UTF-8 text instead of silently accepting malformed input. This page is an encoder and decoder only; it does not validate JWT claims, verify signatures, encrypt data, sign payloads, or prove that decoded content is trustworthy.
