How to Use the JWT Decoder

Paste your JWT — the full xxxxx.yyyyy.zzzzz string — into the input field.

The tool splits the token into its three parts, Base64URL-decodes the header and payload, and displays them as formatted JSON.

Inspect the claims, expiry, issuer, and any other fields in the payload.

What Is a JWT?

A JSON Web Token (JWT) is a compact, URL-safe token format defined in RFC 7519, used to transmit claims between parties. A JWT consists of three Base64URL-encoded parts separated by dots: a header (specifying the algorithm), a payload (containing the claims), and a signature. The header and payload are plain JSON — only the signature is cryptographic. JWTs are widely used in authentication systems, OAuth 2.0 flows, and API authorization, typically passed as a Bearer token in the Authorization header.

When to Use This Tool

Debugging authentication flows — Inspect the claims in a JWT to verify the issuer, subject, expiry time, and custom claims without writing decode logic.

Checking token expiry — Decode the exp claim to confirm whether a token has expired or is still valid.

Understanding third-party tokens — Decode JWTs from OAuth providers, identity platforms, or APIs to understand their structure and claims.

Development and testing — Quickly inspect tokens during local development without needing a library or debugger.

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