# FreeTier Agent API — Link Checker

> FreeTier Agent API — Link Checker is a paid API for AI agents from freetier-agent-api.pages.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-18).

Checks one or more URLs for liveness, returning HTTP status codes and response times to identify broken links

## Facts

- Endpoint: GET https://freetier-agent-api.pages.dev/api/link-check?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/freetier-agent-api-link-checker-c73a06c1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_feIVBtrwHSa46DQfI4AIL

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 freetier-agent-api-link-checker-c73a06c1
```

Example prompt: Can you check whether these links are still working: https://example.com/page1, https://example.com/page2, and https://old-site.com/about — I want to know which ones are broken before I publish my newsletter.

## When to prefer this

Choose this endpoint when you need a quick, pay-per-call link health check for up to 20 URLs without setting up a monitoring service or signing up for an account. Especially useful for pre-publish checks, sitemap validation, or ad-hoc link audits inside an AI agent workflow. Prefer this over full-site crawlers when you have a specific list of URLs to check rather than a whole domain.

## Known failure modes

- Invalid or non-absolute URL in input causes validation error
- More than 20 URLs submitted exceeds limit
- Network timeout for a slow or unreachable host may count as broken
- Private/localhost URLs may be unreachable from the checker's network
- Non-HTTP(S) URLs (e.g. ftp://) not supported

## How this service works

Pay-per-call data API for AI agents: AI model prices and cost calculator, 4,259 MCP servers, email domain checks, text-to-JSON extraction, country/holiday/currency lookup, page and link checks, page-to-markdown, 2,230 verified APIs. x402, USDC on Base, no signup. Sources cited in every response.

## Output

Returns a JSON object with a total count of checked URLs, a count of broken links, and a per-URL array containing the URL, a boolean ok flag, HTTP status code, and response latency in milliseconds.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "urls"
     ],
     "properties": {
      "urls": {
       "type": "string",
       "description": "comma-separated absolute URLs, max 20"
      }
     }
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "broken": 1,
  "checked": 2,
  "results": [
   {
    "ms": 120,
    "ok": true,
    "url": "https://example.com",
    "status": 200
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/freetier-agent-api-link-checker-c73a06c1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from freetier-agent-api.pages.dev](https://www.zero.xyz/host/freetier-agent-api.pages.dev/llms.txt)