How is Base64URL different from standard Base64?

Base64URL (RFC 4648 §5) replaces the + and / characters with - and _, and omits the trailing = padding, so the result is safe to use inside URLs and filenames without escaping.

Can it decode JWT segments?

Yes. JWT header and payload segments are Base64URL-encoded, so you can paste a segment into Decode mode to read its raw JSON.

Is my data uploaded anywhere?

No. Encoding and decoding happen entirely in your browser using the built-in TextEncoder and atob/btoa functions.

Base64 URL-Safe Encoder

Encode and decode Base64URL (RFC 4648 §5) for tokens and URLs.

Base64URL encoder and decoder

Base64URL is the URL- and filename-safe variant of Base64 defined in RFC 4648 §5. It swaps the two problematic characters — + becomes - and / becomes _ — and drops the trailing = padding, so the encoded string can travel inside a URL query string or a JWT without any extra percent-escaping.

Switch between encode and decode, paste your input, and the result updates instantly — everything runs locally in your browser.