# Cited Brief – Check Links

> Cited Brief – Check Links is a paid API for AI agents from cited-brief.cited-brief.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-18).

Checks up to 10 public URLs for reachability, HTTP status, redirects, and content metadata

## Facts

- Endpoint: POST https://cited-brief.cited-brief.workers.dev/check-links?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cited-brief-check-links-6d7acaf9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yF27VDI7IPbm4seiGwwYC

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 cited-brief-check-links-6d7acaf9 -d '<json body>'
```

Example prompt: Can you check whether these three URLs are still live and tell me if any of them are broken or redirecting somewhere unexpected: https://example.com/pricing, https://example.com/old-page, and https://example.com/about?

## When to prefer this

Choose this endpoint when you need lightweight, fast HTTP-level reachability checks on a batch of up to 10 URLs — especially for citation validation, broken-link detection, or redirect auditing — and you want per-call pricing with no subscription. It is not a full page scraper; prefer it when you only need status codes, titles, redirects, and reachability rather than full page content or rendered JavaScript.

## Known failure modes

- Non-public or firewall-protected URLs may return errors even if the page exists
- URLs that take longer than the worker timeout to respond may fail
- More than 10 URLs in a single request will be rejected by schema validation
- Malformed or non-HTTP(S) URLs will likely error or return unexpected states
- Payment failure via x402 will block the call before any URLs are checked

## How this service works

Pay-per-call web research tools for AI agents, paid in USDC over x402.

## Output

Returns a JSON object with a count of successful checks and an array of per-URL results, each including: whether the URL was reachable (ok), the HTTP status code, the final URL after any redirects, the page title, the content type, any redirect chain, the last-modified header if available, and a human-readable state label (e.g. 'ok', 'not_found').

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "urls": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 10,
   "minItems": 1,
   "description": "Public http(s) URLs to check"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": 1,
  "checked": 2,
  "results": [
   {
    "ok": true,
    "url": "https://example.com/pricing",
    "state": "ok",
    "title": "Pricing",
    "status": 200,
    "final_url": "https://example.com/pricing",
    "redirects": [],
    "content_type": "text/html",
    "last_modified": null
   },
   {
    "ok": false,
    "url": "https://example.com/retired-page",
    "state": "not_found",
    "title": null,
    "status": 404,
    "final_url": "https://example.com/retired-page",
    "redirects": [],
    "content_type": "text/html",
    "last_modified": null
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cited-brief-check-links-6d7acaf9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from cited-brief.cited-brief.workers.dev](https://www.zero.xyz/host/cited-brief.cited-brief.workers.dev/llms.txt)