JWT Decoder for Header and Payload
Inspect JSON Web Token header and payload segments locally while debugging authentication examples, claims, and token-shaped data.
A JWT decoder reads the header and payload sections of a JSON Web Token.
Decoding makes claims readable, but it does not prove the token is valid or trusted.
Use development tokens
Avoid pasting sensitive production tokens unless you have a clear local debugging reason.
Treat output as untrusted
Readable claims still need signature, issuer, audience, and expiration validation.
The signature segment is shown only as token text and is not verified.
Use decoded claims for inspection, not for security decisions.
A valid-looking payload does not prove that a token is trusted.
Signature, issuer, audience, expiration, and key rotation must be checked by your application.
Example
Paste a development JWT and inspect claim names before wiring authorization logic.
Assumption
The token uses the common three-part JWT structure with JSON header and payload.
Limitation
This tool does not verify signatures, trust, expiration, issuer, or audience.
Claim debugging
Inspect issuer, audience, subject, expiration, scopes, and custom claims.
Auth examples
Decode sample tokens while writing docs, tickets, or test notes.
Header checks
Review algorithm and key ID fields before looking at application validation.
Payload formatting
Copy decoded JSON into a formatter for easier review and comparison.
Is this a JWT validator?
No. It is a decoder only.
Can I paste production tokens?
The tool runs locally, but sensitive production tokens should still be handled carefully.
Why is signature verification excluded?
Verification needs trusted keys and application-specific validation rules.
Does it need a backend?
No. Decoding runs in your browser.
Suggested workflow
Token inspection path
Decode token-shaped data, format claims, and compare exact payload text during authentication debugging.