MCP For Claude Marketplace
JWT Decoder & Verifier

JWT Decoder & Verifier MCP Connector for Claude

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Decode and mathematically verify JWT tokens local. Ensure API authentication tokens are cryptographically authentic and not expired.

1 tools Official Updated Jun 28, 2026 Official Vinkius Partner
More Details Connect to Claude

While an AI Agent can base64-decode a JSON Web Token to read its claims, it is physically incapable of verifying the cryptographic signature. This means an AI could accept a forged token or an expired session without knowing. This MCP solves that by offloading the mathematical signature verification to the V8 engine.

The Superpowers

  • Cryptographic Verification: Uses jsonwebtoken to strictly verify the token signature against the provided secret key.
  • Local Decoding: Extract user IDs, roles, and expiration dates instantly without network latency.
jwtcryptographic-verificationtoken-validationauthenticationsecuritysignature-check

1 tools expose this connector's capabilities to your AI agent.

decode_jwt

Pass the JWT string and optionally a secret or public key. The engine decodes the header, payload, and validates the signature offline. Decodes JSON Web Tokens (JWT) and mathematically verifies cryptographic signatures offline

See how to talk to your AI agent using JWT Decoder & Verifier.

Decode this JWT token to see what user ID is inside it.

JWT Payload: Decoded successfully. User ID is 123.

Verify this API JWT token using our master secret key.

JWT Result: Cryptographic signature verified successfully.

Check if this authentication token is expired.

JWT Error: TokenExpiredError: jwt expired at 2026-01-01.

Yes, if you omit the secret, it will only decode the payload, but it will not verify authenticity.

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