Base64URL Encode/Decode

URL-safe Base64 encoding used in JWTs and other applications

Input

Output

What is Base64URL?

Base64URL is a URL and filename-safe variant of Base64 encoding. It replaces characters that have special meaning in URLs:

Standard Base64Base64URLReason
+-+ is space in URLs
/_/ is path separator
= (padding)(omitted)= has special meaning in query strings
Common Uses

Base64URL is used in:

  • JSON Web Tokens (JWT) - header and payload encoding
  • JSON Web Keys (JWK) - key material encoding
  • OAuth 2.0 PKCE - code_challenge encoding
  • Data URLs that need to be URL-safe
  • Filenames derived from encoded data