JWT Decoder - Decode, Verify & Debug JSON Web Tokens
Free offline JWT decoder to instantly decode, verify, and debug JWT tokens. Inspect headers, payloads, and signatures with complete privacy.
What is a JWT Token?
A JSON Web Token (JWT) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. JWTs are widely used for authentication and authorization in modern web applications, APIs, and microservices.
Every JWT consists of three parts separated by dots (.):
- Header - Contains the token type (JWT) and the signing algorithm (e.g., HS256, RS256)
- Payload - Contains the claims, which are statements about the user and additional metadata
- Signature - Verifies the token has not been tampered with and authenticates the sender
Example JWT structure: xxxxx.yyyyy.zzzzz
How to Decode a JWT Token
Decoding a JWT is simple with SelfDevKit. Follow these steps:
- Paste your JWT - Copy your JWT token and paste it into the input field
- View decoded data - The header and payload are automatically decoded and displayed in a readable JSON format
- Verify signature (optional) - Enter your secret key or public key to verify the token's signature
- Inspect claims - Review the payload claims including expiration time (exp), issued at (iat), and custom claims
JWT Decoder Features
Decode JWT Instantly
Paste any JWT token to instantly view the decoded header and payload. See all claims, expiration times, and metadata in a clean JSON format.
Verify JWT Signatures
Verify token signatures using secret keys (HMAC) or public keys (RSA/ECDSA). Confirm your tokens are valid and untampered.
All Algorithms Supported
Full support for HS256, HS384, HS512, RS256, RS384, RS512, ES256, ES384, ES512, PS256, PS384, and PS512 algorithms.
100% Offline & Private
Your tokens never leave your device. All decoding and verification happens locally, making it safe for production tokens.
Create & Sign JWTs
Generate new JWT tokens for testing. Specify custom headers, payloads, and sign with your preferred algorithm.
Debug JWT Issues
Quickly identify issues with expired tokens, invalid signatures, or malformed JWTs. Perfect for debugging authentication flows.
Common Use Cases for JWT Decoder
- Debug authentication issues - Inspect token claims to troubleshoot login and session problems
- Verify token expiration - Check exp and iat claims to understand token validity
- Test API integrations - Decode tokens from OAuth providers to verify correct claims
- Security auditing - Review what data is stored in tokens and ensure no sensitive information is exposed
- Development and testing - Generate test tokens with specific claims for development environments
Frequently Asked Questions
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