# RelayStation JWT Verify

> RelayStation JWT Verify is a paid API for AI agents from api.relaystation.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Verifies a JWT signature with algorithm pinning, blocking alg:none and algorithm confusion attacks, without logging the key.

## Facts

- Endpoint: POST https://api.relaystation.ai/v1/utils/jwt-verify
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/relaystation-jwt-verify-daf16de7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7ac5f0G_Cj6KpqkSc5CTO

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability relaystation-jwt-verify-daf16de7 -d '<json body>'
```

Example prompt: Can you verify this JWT token — eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0In0.abc123 — using HS256 and my secret key 'my-super-secret'? Make sure the algorithm is pinned to HS256 so no downgrade is possible.

## When to prefer this

Choose this endpoint when you need a fast, security-hardened JWT verification that explicitly blocks alg:none attacks and algorithm confusion vulnerabilities, and when you require that the signing key is never logged or persisted. Ideal for agent pipelines, middleware, and serverless environments where you want a simple pay-per-call verification without managing a crypto library.

## Known failure modes

- Invalid signature — token has been tampered with or wrong key provided
- Algorithm mismatch — token header alg does not match pinned alg parameter
- Malformed JWT — token is not a valid three-part JWT structure
- Expired token — exp claim has passed (if claims validation is included)
- Missing required fields — token, key, or alg not provided
- Unsupported algorithm — alg value outside allowed enum set

## How this service works

$0.0001/call. Verify a JWT signature — algorithm-pinned; the key is never logged. 1¢ x402 min; remainder auto-credits — relaystation.ai/penny

## Output

Returns whether the JWT signature is valid, along with the decoded header and payload claims if verification succeeds. Algorithm is pinned to the specified value, preventing alg:none and algorithm confusion downgrades. The verification key is never logged.

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "type": "object",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "type": "string",
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ]
    },
    "bodyType": {
     "type": "string",
     "enum": [
      "json",
      "form-data",
      "text"
     ]
    },
    "body": {
     "type": "object",
     "properties": {
      "token": {
       "type": "string",
       "minLength": 1
      },
      "key": {
       "type": "string",
       "minLength": 1,
       "description": "The verification key (secret/PEM/JWK string) — never logged."
      },
      "alg": {
       "type": "string",
       "enum": [
        "HS256",
        "HS384",
        "HS512",
        "RS256",
        "RS384",
        "RS512",
        "ES256",
        "ES384"
       ],
       "description": "The verify is pinned to this alg (alg:none and confusion downgrades blocked)."
      }
     }
    }
   },
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   },
   "required": [
    "type"
   ]
  }
 },
 "required": [
  "input"
 ]
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/relaystation-jwt-verify-daf16de7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.relaystation.ai](https://www.zero.xyz/host/api.relaystation.ai/llms.txt)