JWT Decoder
Decode and inspect JWT tokens
What is JWT Decoder?
JSON Web Token (JWT) Decoder parses and validates JWTs — a compact, URL-safe means of representing claims between two parties. JWTs are commonly used for authentication and authorization in web applications.
When to use this tool
- Debugging API authentication issues
- Inspecting token claims and expiration
- Verifying JWT structure before sending
- Understanding OAuth/OIDC flows
- Debugging session tokens
How it works
A JWT has three Base64URL-encoded parts separated by dots: Header (algorithm), Payload (claims), and Signature (verification). This tool decodes the header and payload, shows expiration status, and validates the signature if you provide a secret key.
Security Guidelines
- Never put sensitive data in JWT payload — it is only encoded, not encrypted
- Check expiration (exp) and issued-at (iat) claims
- Verify the algorithm (alg) claim — "none" algorithm is a security risk
- Use RS256 (asymmetric) instead of HS256 (symmetric) for distributed systems
About JWT Decoder
Decode and inspect JWT tokens It runs entirely in your browser — no files are uploaded to any server, ensuring complete privacy and instant results.
- •Encode and decode Base64, URL, and HTML entities
- •Supports text and file inputs
- •Instant conversion with no server upload
- •Works offline in your browser
Last updated: 2025-01-15
FAQ
Decode and inspect JWT tokens
Yes, completely free. No signup required.
Yes. Runs entirely in your browser, no files uploaded.
Yes, works on any device with a modern browser.
No, everything runs in your browser.