JWT Decoder
Decode JSON Web Tokens (JWT) payload structures. Inspect header tokens, custom attributes, and expiration thresholds instantly.
How JSON Web Tokens Work
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. Since JWTs are signed, the receiver can trust the authenticity of the payload contents.
JWTs are split into three parts separated by dots: Header (meta/alg), Payload (claims), and Signature. Because the payload is simply Base64Url-encoded, anyone can decode the token to view the claim values. Our client-side decoder converts these strings back to JSON formats, displaying token lifetime states in real-time.
Frequently Asked Questions
Is it safe to decode my API tokens here?
Yes. The decoding process runs 100% locally in your web browser. No token keys or signature strings are transmitted to our servers or stored anywhere.
Can this tool verify the signature of my token?
This tool runs fully client-side and does not verify signature cryptography against private keys (which would require sending your secret key). It decodes the JSON payload and header segments for inspection.
What do 'exp', 'iat', and 'nbf' fields mean?
These are standard JWT claims: 'exp' is the expiration time (epoch seconds), 'iat' is the time the token was issued, and 'nbf' is the 'not before' activation time.