JWT Decoder - Decode JWT Tokens
Decode and analyze JSON Web Tokens in real-time
Privacy & Security
🔒 This tool works entirely in your browser. JWT tokens are NOT sent to the server and remain private on your device.
What is a JWT Token?
A 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. It is commonly used for authentication and secure information exchange in modern web applications.
JWT Structure
A JWT consists of three parts separated by dots (.):
- Header - contains the token type and signing algorithm (e.g., HS256, RS256)
- Payload - contains the claims (statements) about user data and metadata
- Signature - verifies that the token has not been tampered with
Security & Best Practices
- Never store sensitive data in the payload (it's decodable by anyone)
- Always use HTTPS to transmit JWT tokens
- Set short expiration times for tokens (exp claim)
- Always verify the signature on the server
- Use secure algorithms like RS256 or ES256
Common Use Cases
- Authentication - Single Sign-On (SSO), API authentication
- Authorization - Role-Based Access Control (RBAC)
- Information Exchange - Secure data transmission between microservices
Standard Claims
Common registered claims in JWT:
iss(Issuer) - Who issued the tokensub(Subject) - Subject of the token (e.g., user ID)aud(Audience) - Token recipientsexp(Expiration) - Expiration timestampiat(Issued At) - Issuance timestamp