JWT HMAC Signature Verifier

x402

JWT HMAC Signature Verifier is a paid API for AI agents from agent402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Verifies an HS256, HS384, or HS512 JWT signature against a shared secret and checks token expiry, returning validity status and the decoded payload.

Price / call$0.001

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Success—

StatusUnknown

How this service works

Verify an HS256/384/512 JWT signature against a secret and check expiry. Returns valid + decoded payload. (HMAC algorithms only.)

Output

Returns a boolean validity flag indicating whether the HMAC signature is correct and the token is not expired, along with the fully decoded JWT payload (header + claims) if valid.

Example use cases

Example prompt

“Can you verify this JWT token for me — 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0.dozjgNryP4J3jVmNHl0w5N_XgL0n3I9PlFUP0THsR8U' — using the secret 'mySuperSecretKey123' and tell me if it's valid and what the payload says?”

Technical details

Endpoint

POSThttps://agent402.tools/api/jwt-verify

When to prefer

Use this endpoint when you need to verify HMAC-signed JWTs (HS256, HS384, or HS512) server-side without running your own cryptographic library. Ideal for agents that receive tokens from users or upstream services and need to confirm authenticity and freshness before trusting the embedded claims. Not suitable for asymmetric JWT algorithms like RS256 or ES256.

Side effects

Invalid or malformed JWT format — token cannot be parsed
Wrong secret provided — signature verification fails, valid=false returned
Expired token — expiry check fails even if signature is correct
Unsupported algorithm (e.g. RS256, ES256) — HMAC-only endpoint rejects non-HMAC tokens
Missing required fields (token or secret) — request rejected with validation error
Network timeout or service unavailability

Input

Schema · Request body

Field	Type	Description
token	string
secret	string

Output

Schema · Response

{
  "type": "json",
  "example": {
    "valid": true,
    "expired": false,
    "payload": {
      "sub": "agent402"
    },
    "algorithm": "HS256"
  }
}

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How this service works

Verify an HS256/384/512 JWT signature against a secret and check expiry. Returns valid + decoded payload. (HMAC algorithms only.)

Output

Returns a boolean validity flag indicating whether the HMAC signature is correct and the token is not expired, along with the fully decoded JWT payload (header + claims) if valid.

Technical details

Endpoint

POSThttps://agent402.tools/api/jwt-verify

When to prefer

Side effects

Invalid or malformed JWT format — token cannot be parsed
Wrong secret provided — signature verification fails, valid=false returned
Expired token — expiry check fails even if signature is correct
Unsupported algorithm (e.g. RS256, ES256) — HMAC-only endpoint rejects non-HMAC tokens
Missing required fields (token or secret) — request rejected with validation error
Network timeout or service unavailability

Input

Schema · Request body

Field	Type	Description
token	string
secret	string

Output

Schema · Response

{
  "type": "json",
  "example": {
    "valid": true,
    "expired": false,
    "payload": {
      "sub": "agent402"
    },
    "algorithm": "HS256"
  }
}