# x402 Preflight Endpoint Validator

> x402 Preflight Endpoint Validator is a paid API for AI agents from predator-ubuntu.taild9a745.ts.net, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-20).

Validates an endpoint's 402 challenge response, payment schema, and header sizes before listing it on x402-compatible marketplaces

## Facts

- Endpoint: POST https://predator-ubuntu.taild9a745.ts.net/v1/preflight?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-preflight-endpoint-validator-8c22b112
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fY5OiC8x_am_eqqOE4TBL

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 x402-preflight-endpoint-validator-8c22b112 -d '<json body>'
```

Example prompt: Run a preflight check on my endpoint at https://api.example.com/data using a GET request to make sure its 402 challenge, headers, and payment schema are all valid before I list it.

## When to prefer this

Use this endpoint when you are a developer or agent preparing to list an x402-enabled API on a marketplace and need to validate that the 402 challenge, payment schema, and headers are correctly configured before submission. Prefer this over manual testing when you want a structured, automated report of compliance issues.

## Known failure modes

- Target URL is unreachable or times out
- Target endpoint does not return a 402 status at all
- Payment schema fields are malformed or missing required properties
- Response headers exceed size limits
- Invalid URL format provided as input
- Target endpoint returns unexpected redirects

## How this service works

x402 pre-listing QA probe: validate your endpoint's 402 challenge, header sizes, and payment schema before listing

## Output

Returns a structured report indicating whether the target endpoint correctly issues a 402 Payment Required challenge, whether the payment schema fields are valid and complete, and whether response headers are within acceptable size limits — surfacing any issues before the endpoint is listed on an x402 marketplace.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri"
  },
  "body": {
   "type": "object"
  },
  "method": {
   "enum": [
    "GET",
    "POST"
   ],
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-preflight-endpoint-validator-8c22b112/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from predator-ubuntu.taild9a745.ts.net](https://www.zero.xyz/host/predator-ubuntu.taild9a745.ts.net/llms.txt)