Decode and inspect JSON Web Token (JWT) header, payload, and signature online. Free JWT decoder — instantly view token claims and structure. No signup required.
JWT tokens are used for authentication and authorisation in virtually every modern web application. When debugging login flows, inspecting tokens from OAuth providers, or investigating why an API is returning 401 Unauthorized errors, you need to quickly read the token contents without writing code. This tool decodes all three JWT sections — header, payload, and signature — and displays the expiry time, issuer, and all custom claims in a readable format.
All processing for JWT Decoder runs entirely in your browser. Your data — whether text, files, or other content — is never transmitted to any server. DevToolHub has no backend that receives or stores your inputs. This means the tool works even offline once the page has loaded, and there is no risk of your data being intercepted or stored by a third party.
Does this tool validate the JWT signature?
No. This is a decoder, not a validator. It decodes the Base64Url parts to show what is inside, but cannot verify the signature because it does not have the secret key used to sign the token. Never trust a JWT in production without first verifying its signature server-side.
What are claims in the payload?
Claims are statements about a subject. Registered claims like iss (issuer), exp (expiration time), and sub (subject) are standard. You can also include private claims — custom data specific to your application such as userId or roles.
Is it safe to paste a real JWT here?
Decoding runs entirely in your browser — the token is never sent to any server. That said, treat JWTs as sensitive credentials. For debugging, use tokens from a staging environment or generate a test token instead.
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