About Base64URL Encoder

Encode URL-safe base64 — + → - , / → _ , no padding. Part of the DevTools Surf developer suite. Browse more tools in the Encoding collection.

Use Cases

• Backend developers encoding JWT payloads for token generation
• Frontend devs passing binary data safely in URL query parameters
• API developers creating URL-safe identifiers from binary hashes
• Security engineers encoding cryptographic signatures for URL transport

Tips

• Use this instead of standard Base64 when encoding JWT segments or URL params
• Check that the output has no +, /, or = characters for URL safety
• Compare output with standard Base64 to see the character substitutions

Fun Facts

• Base64URL encoding is defined in RFC 4648 Section 5 (2006), specifically designed to be safe in URLs and filenames by replacing + with - and / with _.
• JWTs use Base64URL (not standard Base64) for all three segments — header, payload, and signature — to ensure tokens are safe in URL query parameters.
• Standard Base64 adds = padding to make output a multiple of 4 characters; Base64URL omits padding because the decoder can infer the original length.

FAQ

When should I use Base64URL vs regular?

In URLs (query strings, path segments), JWTs, JWS, and anywhere +/= would need additional percent-encoding.

Is padding removed?

Yes by default (matches JWT spec). Toggle 'include padding' if your consumer requires trailing =.

Can I mix with regular Base64?

Not safely. Some decoders accept both; many don't. Pick one variant per context.

Does it support binary input?

Yes — upload a file. Useful for embedding binary in JSON-over-URL patterns.