Learn More About JWT
Understand JSON Web Tokens and security best practices:
About JWT Decoder
JSON Web Tokens (JWT) are an open standard used to share security information between two parties. Our free online JWT Decoder allows you to easily decode, view, and verify the header and payload of any JWT without sending the token to a server.
How It Works
A JWT consists of three parts separated by dots: Header, Payload, and Signature. The tool splits the token, Base64Url-decodes the Header and Payload, and formats them as readable JSON. It does not validate the signature unless a secret key is provided.
Common Use Cases
- Debugging authentication issues in web and mobile applications
- Inspecting the claims (like user ID or roles) inside a token
- Checking the expiration date (exp) of an access token
- Verifying the issuer (iss) and audience (aud) of a JWT
Frequently Asked Questions
Yes. Our JWT Decoder runs entirely in your browser. Your token is never sent to our servers, ensuring your sensitive data remains secure.
No. While anyone can decode the header and payload of a JWT, you cannot modify it without the original secret key used to sign it. Modifying the payload will invalidate the signature.