# URL Preflight Check

> URL Preflight Check is a paid API for AI agents from x240.jvnclk88.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-29).

Fetches a URL and returns its HTTP status, full redirect chain, key response headers, response time, robots.txt rules for the path, and sitemap location

## Facts

- Endpoint: POST https://x240.jvnclk88.workers.dev/url/check?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/url-preflight-check-e27188a6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ySPuYhKuYVcOo84Jbw2BV

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 url-preflight-check-e27188a6 -d '<json body>'
```

Example prompt: Before I scrape it, can you do a preflight check on https://example.com/pricing — I want to know if it's reachable, whether it redirects anywhere, how fast it responds, and whether it's blocked by robots.txt?

## When to prefer this

Use this endpoint when you need to verify a URL's reachability, understand its redirect behavior, check its robots.txt accessibility rules, or gather key HTTP headers before committing to a full scrape or crawl. It is ideal as a preflight step in any web automation pipeline to avoid wasting resources on dead links, redirect loops, or blocked pages.

## Known failure modes

- Invalid or malformed URL returns a validation error
- Private or non-public URLs (e.g. localhost, internal IPs) are rejected
- DNS resolution failures result in a connection error response
- Very slow or timing-out URLs may return a timeout error
- Some servers block automated requests (403 Forbidden) which is reflected in the status

## How this service works

URL preflight - status, redirect chain, key headers, response time, robots.txt rules for the path and sitemap location

## Output

Returns a JSON object containing the final HTTP status code, the complete redirect chain (each hop's URL and status), key response headers (e.g. Content-Type, Cache-Control, X-Robots-Tag), the total response time in milliseconds, the robots.txt rules applicable to the requested path (allow/disallow), and the sitemap URL if discoverable.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Public http or https URL to fetch"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/url-preflight-check-e27188a6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x240.jvnclk88.workers.dev](https://www.zero.xyz/host/x240.jvnclk88.workers.dev/llms.txt)