JWT Decoder

JWT Decoder splits a JSON Web Token into its three parts — header, payload, and signature — and decodes the base64url-encoded JSON so you can read what's inside. It annotates the standard registered claims (iss, sub, aud, exp, nbf, iat, jti) with human-readable labels and converts the timestamp claims into local dates. Expired and not-yet-active tokens are flagged at a glance. The tool runs entirely in your browser. The token is never uploaded, logged, or stored, which makes it safe for tokens scraped from internal logs, customer reports, or production debugging sessions. Note that this tool does not verify the JWT signature. JWTs are encoded, not encrypted — anyone with the token can read its contents. Verifying authenticity requires the signing secret or public key, which intentionally lives on your server, not in a public web tool. If you need to verify a token, do it server-side with a library that validates the signature against your key. Common uses include checking the expiration of an access token that's mysteriously failing, confirming what scopes or roles are baked into a token, debugging the difference between two tokens issued to the same user, and reading the audience or issuer claim when integrating with a third-party identity provider.