Base64URL Encode Decode
RFC 4648 §5A live base64url encode decode tool. Generates url safe base64 strings with no padding and using hyphen and underscore characters.
What is Base64URL and why is it used under RFC 4648 §5?
This tool operates as a versatile base64url encode decode and url safe base64. Base64URL is a modified standard of standard Base64 defined in section 5 of RFC 4648. It replaces standard unsafe URL characters: plus (+) is changed to minus (-), slash (/) is changed to underscore (_), and the equals (=) padding character is deleted. This allows the encoded text to be passed safely inside URLs or file systems without needing extra URL encoding steps.
How does this two-way Base64URL converter differ from standard Base64?
A standard base64 converter outputs plus and slash characters, which require escaping in URLs. This base64url converter maps standard characters to a URL-safe alphabet and removes padding entirely. The live interface allows developers to inspect both formats seamlessly, validating and decoding strings on the fly.
Why do JSON Web Tokens use URL-safe Base64 encoding?
JSON Web Tokens (JWT) are designed to be sent inside HTTP authorization headers and query string parameters. Because standard Base64 characters like plus (+) and slash (/) are reserved in URLs and cause parsing errors, RFC 7519 mandates that all three segments of a JWT must be Base64URL-encoded.
Frequently Asked Questions
What is the benefit of base64url encode decode over standard Base64?
Base64URL encode decode replaces standard characters + and / with - and _ to make the output safe for URL query parameters and JWT tokens.