What This Tool Does
This browser-based JWT decoder splits a token into header, payload, and signature parts, decodes the Base64URL JSON, formats the header and payload, and highlights common claims such as alg, typ, iss, sub, aud, iat, nbf, and exp.
MV ToolsJWT tool
JWT Decoder Online
Decode the header and payload of a JSON Web Token directly in your browser without uploading the token.
JWT Decoder Online
Decode JSON Web Token header and payload claims locally in your browser for API debugging, authentication testing, and token inspection.
Common Use Cases
- Inspecting JWT payload claims from an API response or authentication flow
- Checking exp, iat, and nbf timestamps while debugging token lifetime issues
- Reading JWT header values such as alg, typ, and kid without uploading the token
How Data Is Handled
JWT decoding runs entirely in your browser. The token is not uploaded to the backend, and the signature is displayed but not verified.
FAQ
Does this verify the JWT signature?
No. This first version decodes and displays the token only. It does not verify whether the signature is valid.
Is my JWT sent to the server?
No. Header and payload decoding run locally in your browser.
Can I decode expired tokens?
Yes. The tool can decode expired tokens and shows whether an exp claim is already in the past.