JWT Decoder

How to use JWT Decoder

1. Paste a JWT with three dot-separated segments.
2. Select Decode token.
3. Read the formatted header and payload JSON.
4. Use the signature segment only as a visual reference; this MVP does not verify signatures.

Why this tool exists

A JWT decoder helps you inspect the structure of a JSON Web Token. JWTs are commonly used for authentication, session state, API authorization, and service-to-service claims. A token normally has three dot-separated segments: header, payload, and signature. This tool decodes the first two segments so you can read the algorithm, token type, issuer, subject, audience, expiration, and custom claims.

Decoding a JWT is not the same as verifying it. The header and payload are Base64URL-encoded JSON, which means they are meant to be readable by anyone who has the token. The signature proves whether the token was issued by a trusted party, but verifying that signature requires the correct secret or public key. MVP intentionally avoids accepting verification keys so the page stays focused on safe local inspection.

Treat real JWTs as sensitive. A token can grant access even when the payload looks harmless. If a token came from a production browser session, a mobile app, a server log, or a customer support conversation, do not paste it into random online tools. CleanWebTools decodes locally in the browser, but your operational habit should still be conservative: redact, use test tokens where possible, and clear the input after inspection.

Use this page when you need to quickly understand claims, expiration timestamps, or token shape while debugging. If you need to format nested JSON after decoding, use the JSON Formatter page.

Common examples

• Check whether a token is expired by reading the exp claim.
• Inspect which issuer and audience a token was created for.
• Confirm whether a custom claim is present during API debugging.

FAQ