Learn More About JWT
Understand JSON Web Tokens and security best practices:
JWT Decoder & Parser Online
Decode, parse, and inspect JSON Web Tokens (JWT) instantly. View the header, payload, and signature of your JWTs securely in your browser. Free online JWT tool for developers.
How It Works
A JWT consists of three parts separated by dots: Header, Payload, and Signature. Our tool splits the token, Base64-decodes the Header and Payload, and formats them as readable JSON. It does not verify the signature unless you provide the secret key.
Common Use Cases
- Inspecting the claims (like user ID or roles) inside a JWT payload during development
- Debugging authentication and authorization issues in web applications
- Checking the expiration time (exp) of a token to see if it has expired
- Verifying the algorithm (alg) used to sign the token in the header
Frequently Asked Questions
Yes. Our JWT decoder runs entirely on the client-side (in your browser). Your tokens are never sent to our servers. However, as a best practice, you should never paste production tokens containing highly sensitive data into any online tool.
This specific tool is primarily for decoding and inspecting the contents. To verify the signature, you would need to use a JWT verification tool and provide the corresponding secret key or public key.
Ensure your token is a valid JWT. It must contain exactly three Base64-encoded strings separated by two dots (.). If it is malformed or not a JWT, it cannot be decoded.
A JWT has three parts: the Header (algorithm and type), the Payload (claims like user ID, expiration, issuer), and the Signature (verification). Our tool decodes and displays all three.
Yes, the tool reads the 'exp' (expiration) claim and displays it as a human-readable date and time. It also shows whether the token is currently expired.
Yes, decoding happens entirely in your browser. The JWT is never sent to any server. However, be cautious about sharing tokens that contain sensitive claims.
Decoding simply reads the Header and Payload (which are Base64-encoded, not encrypted). Verifying checks the Signature against a secret/public key to confirm authenticity.