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JWT Decoder

Paste a JSON Web Token to instantly view its decoded header, payload, and expiration claims. Everything is decoded locally in your browser, so no token ever leaves your device.

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About JWT Decoder

JWT Decoder is a free online tool for inspecting JSON Web Tokens without leaving your browser. Paste any token and it instantly splits the three base64url segments, decodes the header and payload, and displays them as readable JSON so you can debug authentication flows, inspect API responses, or verify claim values while developing.

Unlike many JWT debuggers that quietly log or transmit pasted tokens, this decoder runs entirely as client-side JavaScript. Your access tokens, refresh tokens, and session claims are decoded locally and are never sent to Neuctra Tools or any third-party server.

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How to Use the JWT Decoder

  1. Paste a full JWT into the token field above.
  2. Review the decoded Header and Payload panels, each with a one-click copy button.
  3. Check the Standard Claims section for human-readable exp, iat, and nbf dates alongside their raw unix timestamps.
  4. Optionally enter a shared secret to verify an HS256 signature directly in your browser.

Built for Debugging and Privacy

Instant Claim Insight

See expiration status, issuer, subject, and audience claims at a glance without writing a single line of decoding code.

No Server, No Logs

Tokens often carry sensitive session data. Decoding locally means nothing you paste is ever stored or transmitted anywhere.

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Who Should Use This Tool

  • Backend Developers debugging authentication middleware and token issuance logic.
  • Frontend Developers inspecting access tokens returned from a login or OAuth flow.
  • QA Engineers verifying that claims such as roles, scopes, or expiration are set correctly.
  • Security Reviewers auditing token contents and expiration policies before shipping.

Privacy First

JWT Decoder never uploads, stores, or transmits any token you paste. All parsing and optional signature checks run inside your browser using standard JavaScript and the Web Crypto API, so sensitive session data stays entirely on your device.

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Yes, this JWT decoder is completely free with no sign-up, rate limits, or premium tier. Paste any JSON Web Token to instantly view its header, payload, and claims at no cost.
No, decoding only reads the header and payload; it does not confirm the signature was issued by a trusted server. Use the optional HMAC verification below to check an HS256 signature against a shared secret you provide.
No, every token stays in your browser and is never uploaded or transmitted anywhere. All base64url decoding, JSON parsing, and optional signature checks run entirely with local client-side JavaScript.
This usually means the pasted text is missing a segment, was truncated, or is not actually a JWT. A valid JSON Web Token always has three base64url segments separated by two periods, so check for extra whitespace or a cut-off string.
The Expired badge appears when the token's exp claim is a timestamp earlier than the current time on your device. It is a client-side check only, so always confirm token validity on your server for anything security-sensitive.