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JWT Decoder (Header & Payload Inspector)

Inspect JSON Web Token headers and payload claims with human-readable expiration dates. Client-side only; does not claim to verify signatures without secret.

  • 100% free
  • Files stay on your device
  • No sign-up, no watermark
Security Note: Signature verification is not performed. Verifying a JWT signature requires a private or shared secret, which should never be entered into any browser. This tool inspects the Base64URL-encoded Header and Payload entirely in client-side memory.
Encoded Token
Header • Algorithm & Token Type
Awaiting valid token...
Payload • Claims & Data
Awaiting valid token...

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What is JWT Decoder (Header & Payload Inspector)?

Debug authentication workflows and inspect JSON Web Tokens (JWT) without risking credential leaks. Decodes the header and payload claims into formatted JSON, converts Unix timestamps into human-readable dates, and flags token expiration status.

How to use JWT Decoder (Header & Payload Inspector)

  1. 1

    Add your file or input

    Choose a supported file, drag it onto the upload area, or type/paste the data this tool works with.

  2. 2

    Adjust the options

    Pick the output format, quality, size or other settings the tool offers. Defaults work well for most files.

  3. 3

    Process and download

    Run the tool and save the result. Processing happens in your browser, so nothing is uploaded to a server.

Frequently asked questions

Is it safe to paste live production JWTs into this tool?

Yes! Unlike cloud-based JWT debuggers that send your token across the web, this decoder runs 100% locally in your browser. Your sensitive auth tokens, user IDs, and permissions never leave your machine.

How does the tool show token expiration?

The tool extracts the standard "exp" (expiration) and "iat" (issued at) claims, compares them against your local clock, and displays whether the token is currently active or expired.

Can this tool verify the cryptographic HMAC or RSA signature?

You can inspect the signature bytes and algorithm type (HS256, RS256, ES256). For security reasons, signature verification with private keys should always be performed within your secure backend application.

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