JWT Encoder/Decoder

A JSON Web Token is a compact, URL-safe way to represent claims between two parties. A JWT consists of three parts separated by dots: Header (algorithm and token type), Payload (the claims or data), and Signature (for verification). JWTs are commonly used for authentication and information exchange in web applications.

Paste your JWT token (the long string starting with eyJ...) into the input field. The tool automatically decodes and displays the Header and Payload as formatted JSON. It also shows timing claims like expiration and issued-at dates. No data is sent to any server — decoding happens entirely in your browser.

Edit the Header and Payload JSON, select an HMAC algorithm (HS256, HS384, or HS512), enter your secret key, and the tool generates a signed JWT. You can set iat to now and adjust exp with preset buttons (+1h, +24h, +7d).