Base64 / JWT Decoder

About this tool

Decode Base64 strings and JSON Web Tokens in your browser. View the header, payload, signature and exp timestamp in ISO 8601 format. Token decoding runs locally in JavaScript; decoding does not verify the signature.

• Base64 Decoder — decode a Base64 string using atob
• JWT Decoder — inspect the header, payload and signature
• exp → ISO 8601 — display the token expiration time
• Local processing — input data is not sent to a server