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JWT Decoder & Validator

A simple and secure tool for decoding and validating JSON Web Tokens (JWT). Paste your token to instantly see the header and payload. Provide your secret or public key to verify the token's signature and ensure it hasn't been tampered with. The tool automatically checks for common claims like expiry (`exp`) and not-before (`nbf`). All processing is done client-side in your browser, so your tokens are never sent to a server.

Tool Interface

Header

...

Payload

...

Verify Signature

All processing is done securely on your local machine. Your token is never sent to our servers.

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Features
  • Instantly decodes JWT headers and payloads.
  • Verifies signatures using HMAC (HS256/384/512) and RSA/ECDSA (RS/ES256/384/512) algorithms.
  • Automatically checks for expired tokens.
  • Highlights common claims like `exp`, `iat`, and `nbf`.
  • All processing is done securely in your browser.
Frequently Asked Questions

Are my tokens and secrets secure?

Yes. This tool is 100% client-side. All decoding and verification happens on your computer within your browser. Nothing is ever transmitted to our servers.

What key formats are supported?

For HMAC algorithms (HS256, etc.), use a plain text secret. For RSA or ECDSA algorithms (RS256, ES256, etc.), use a PEM-formatted public key (starting with `-----BEGIN PUBLIC KEY-----`).

What does "Signature Verified" mean?

It means the token has not been altered and was signed by someone who possesses the correct private key or secret.