Decode Your JWT Token
Enter your JWT token below to decode its contents. All processing happens locally in your browser - your token is never sent to any server.
Mastering JSON Web Tokens: Complete Guide
What is a JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.
JWT Structure
A JWT consists of three parts separated by dots (.):
- Header - Contains metadata about the token, such as the type of token and the algorithm used to sign it.
- Payload - Contains the claims or the actual data being transmitted.
- Signature - Validates that the token hasn't been altered after being issued.
Common Uses for JWTs
- Authentication and authorization
- Information exchange between parties
- Secure API communication
- Single Sign-On (SSO) implementations
- Stateless session management
JWT Claims Explained
| Claim | Description |
|---|---|
| iss | Issuer of the token |
| sub | Subject of the token |
| aud | Audience of the token |
| exp | Expiration time |
| nbf | Not valid before time |
| iat | Time the token was issued |
| jti | JWT ID |
Security Considerations
While JWTs are a great way to transmit information securely, it's important to remember that the payload is only encoded, not encrypted. Sensitive information should never be stored in a JWT unless it's encrypted. Always verify JWT signatures in production environments.
Best Practices for Using JWTs
- Use strong signing algorithms (e.g., RS256)
- Implement expiration times to limit token validity
- Store tokens securely (e.g., HttpOnly cookies)
- Regularly rotate signing keys
- Monitor for unusual token usage patterns
Real-World Applications of JWTs
🔐 API Authentication
Securely authenticate users and services using JWTs in RESTful APIs.
📱 Mobile Applications
Use JWTs for user sessions in mobile apps, ensuring secure access to resources.
🌐 Single Sign-On (SSO)
Implement SSO solutions using JWTs to streamline user access across multiple applications.