Decode and validate JSON Web Tokens - Inspect header, payload, and signature
Privacy First: All decoding happens locally in your browser. Your JWT never leaves your device.
A JWT is a compact, URL-safe token used for securely transmitting information between parties. It consists of three parts separated by dots: header (algorithm), payload (data), and signature (verification).
JWTs have three parts: 1) Header - contains the algorithm and token type, 2) Payload - contains claims (user data), 3) Signature - ensures token integrity. Format: header.payload.signature
No. Decoding extracts the data inside the token. Verification ensures the signature is valid using the secret key. This tool decodes JWTs but cannot verify signatures (requires server-side secret).
The 'exp' claim in JWT payload indicates token expiration time. This tool shows if a token is expired or still valid. Expired tokens should be rejected by the server.
Anyone can decode and read a JWT, but modifying it without the secret key will invalidate the signature. The server rejects tokens with invalid signatures, so modification is easily detected.
Yes! JWT Decoder is completely free with no registration required. Decode unlimited JWT tokens instantly with full header, payload, and signature inspection.