# PennyRail OpenAPI Mock Response Schema Validator

> PennyRail OpenAPI Mock Response Schema Validator is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status down (last checked 2026-10-31).

Validates a JSON request or response payload against an OpenAPI 3.x or Swagger 2.x operation schema, returning a machine-readable settlement result

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/openapi.mock-response--schema-mock?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-openapi-mock-response-schema-validator-e8a68c61
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Up02GypvCQlAk55MmpBkT

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-schema-validator-e8a68c61 -d '<json body>'
```

Example prompt: Can you check whether this JSON payload I got back from our payments API actually conforms to the OpenAPI 3.x operation schema we defined — validate it and tell me if there are any violations?

## When to prefer this

Choose this endpoint when you need a quick, pay-per-call OpenAPI/Swagger schema validation without standing up your own validator infrastructure. Particularly useful in agent pipelines that need to verify API payloads on-the-fly against operation schemas as part of automated integration testing or CI workflows.

## Known failure modes

- Malformed or missing input object returns a generic error
- Schema not recognized or unsupported OpenAPI version may return validation failure
- Overly permissive response schema (additionalProperties: true) means success responses vary widely
- Network or deployment errors on Vercel may cause 5xx responses
- Ambiguous or incomplete OpenAPI operation definitions may yield false positives

## How this service works

Machine-readable settlement service

## Output

Returns a machine-readable object indicating whether the submitted JSON payload is valid against the provided OpenAPI/Swagger schema, including any validation errors, field violations, or conformance details.

## 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-schema-validator-e8a68c61/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)