Base64 & URL Encoder/Decoder
Encode, decode, and decode JWTs — nothing leaves your browser.
Encode or decode Base64 and URL-encoded strings, or decode a JWT's header and payload to inspect its claims — all directly in your browser, which matters since JWTs and encoded tokens often carry sensitive session data.
How to use this tool
- 1Choose Base64 or URL mode, and Encode or Decode direction using the toggle buttons.
- 2Paste or type your text into the Input box on the left.
- 3The Output box on the right updates instantly as you type.
- 4Click Copy next to the output to copy the result to your clipboard.
Frequently asked questions
What's the difference between Base64 and URL encoding?
Base64 encoding turns arbitrary text or binary data into a compact ASCII string (used in data URLs, auth tokens, etc.). URL encoding (percent-encoding) escapes special characters so text is safe to use inside a URL, like turning a space into %20.
Why did decoding fail with an error?
Decode mode expects input that was actually produced by that encoding. Pasting plain text into Base64 decode, or a string with invalid percent-escapes into URL decode, will throw an error — that's expected, not a bug.
Can I encode non-English text or emoji?
Yes — Base64 encoding here first converts your text to UTF-8 bytes, so accented characters, emoji, and other Unicode text encode and decode correctly.
Is my text sent to a server to be encoded?
No. Encoding and decoding both run using built-in browser functions (btoa/atob and encodeURIComponent) directly in your tab — nothing is uploaded.