# PennyRail OpenAPI Mock Response Validator

> PennyRail OpenAPI Mock Response Validator is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Validates a JSON request or response payload against an OpenAPI 3.x or Swagger 2.x operation schema, returning a mock or validated response

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/openapi.mock-response--openapi-mock-response
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-openapi-mock-response-validator-c3317229
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4Th7xF5CjuFOxGygEo2_I

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 pennyrail-openapi-mock-response-validator-c3317229 -d '<json body>'
```

Example prompt: Can you validate this JSON payload against my OpenAPI 3.x operation schema and tell me if it conforms, and give me a mock response if it does?

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call OpenAPI/Swagger schema validation and mock-response service without standing up your own validation infrastructure. Particularly useful in CI/CD pipelines, agent workflows that build or test APIs dynamically, or frontend development where a backend isn't yet available.

## Known failure modes

- Malformed or missing input JSON payload returns a schema validation error
- Unsupported OpenAPI or Swagger version yields an unrecognized schema error
- Payload that does not conform to the operation schema returns a list of constraint violations
- Empty or null input object may return a required field error
- Network or cold-start latency on Vercel may occasionally cause timeout

## How this service works

Machine-readable settlement service

## Output

Returns a validation result indicating whether the input JSON payload conforms to the specified OpenAPI 3.x or Swagger 2.x operation schema, along with any validation errors and a mock response object where applicable.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-openapi-mock-response-validator-c3317229/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pennyrail.vercel.app](https://www.zero.xyz/host/pennyrail.vercel.app/llms.txt)