What is JWT?
JWT (JSON Web Token) is an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. JWTs are digitally signed using HMAC or RSA, making them verifiable and trustworthy. They consist of three Base64-encoded parts: Header (algorithm and token type), Payload (claims/data), and Signature (verification).
JWTs are self-contained, meaning all necessary information is in the token itself, eliminating the need for database lookups. They're widely used for authentication, authorization, and information exchange in modern web applications, mobile apps, and microservices architectures. JWTs enable stateless authentication, making them perfect for distributed systems and APIs.
Why Use JWT Parser?
Our JWT parser helps developers debug authentication issues, inspect token claims, verify expiration times, and understand JWT structure during development and testing. It decodes the Base64-encoded parts to reveal the header, payload, and signature data in human-readable JSON format.
The tool operates entirely in your browser with client-side processing, ensuring your JWTs never leave your device. This provides maximum security when debugging production tokens or sensitive authentication data, making it safe for analyzing tokens containing user information or private claims.
This tool is essential for backend developers implementing JWT authentication, frontend developers integrating with JWT-based APIs, DevOps engineers debugging authentication flows, security auditors reviewing token implementations, and anyone learning about modern authentication mechanisms.
Common Use Cases
Authentication Debugging: Decode JWTs to inspect claims, expiration times, and issuer information when troubleshooting login issues.
API Development: Verify JWT structure and claims during API development to ensure correct token generation.
Security Auditing: Analyze JWT algorithms, expiration times, and claims to identify security issues or misconfigurations.
Testing & QA: Decode test JWTs to verify correct user roles, permissions, and session data during testing.
Learning & Education: Understand JWT structure, claims, and encoding for educational purposes and certification preparation.
How to Use JWT Parser
Paste your JWT token (three Base64-encoded parts separated by dots) into the input field. The parser automatically decodes and displays the header (algorithm, type), payload (claims like user ID, roles, expiration), and signature information in formatted JSON. Check expiration status and verify the token structure.
Important Note: This tool decodes and displays JWT contents but does not verify signatures. To verify JWT signatures, you need the secret key or public key used to sign the token. Never share JWT secret keys publicly. For production signature verification, use secure backend validation with proper key management.