# Northline WebKit – URL Uptime & Redirect Check

> Northline WebKit – URL Uptime & Redirect Check is a paid API for AI agents from northline-webkit.northline-c86.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-31).

Checks whether a public URL is reachable, follows its redirect chain, measures response time, and grades its security headers.

## Facts

- Endpoint: GET https://northline-webkit.northline-c86.workers.dev/v1/url/check?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/northline-webkit-url-uptime-redirect-check-7f0fd8c5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_gAHmxWMo8_GvxEwJZZodY

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 northline-webkit-url-uptime-redirect-check-7f0fd8c5
```

Example prompt: Can you check if https://github.com/ is actually up, how many redirects it goes through, and what security header grade it gets?

## When to prefer this

Use this endpoint when you need a quick, single-call check on whether a URL is live, what its final destination is after redirects, how fast it responds, and whether its security headers are up to standard. Prefer this over full page-scraping endpoints when you only need reachability/metadata, not page content. Ideal for broken-link detection, redirect-chain auditing, uptime spot-checks, and lightweight security posture reviews — all without needing an API key or subscription.

## Known failure modes

- URL is unreachable or times out — ok: false returned
- Invalid or malformed URL input — validation error
- Private/internal URLs not accessible from the public internet — connection refused
- Rate limiting or firewall blocks the check — may return non-200 status
- Payment not settled via x402 — request rejected before execution

## How this service works

Pay-per-call web and domain utilities for AI agents: URL to Markdown, link preview metadata, links, uptime/redirect check, DNS, email-domain check, WHOIS/RDAP, robots.txt and a one-call domain report. x402 (USDC on Base), no API key, no signup.

## Output

A JSON object with: ok (boolean reachability), status (HTTP status code of final response), finalUrl (URL after following all redirects), redirects (count of redirects followed), responseMs (end-to-end latency in milliseconds), and securityHeaders.grade (letter grade reflecting presence of security headers like HSTS, CSP, etc.).

## 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": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string",
       "minLength": 3,
       "description": "Public http(s) URL (scheme optional)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "status": 200,
  "finalUrl": "https://github.com/",
  "redirects": 1,
  "responseMs": 180,
  "securityHeaders": {
   "grade": "A"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/northline-webkit-url-uptime-redirect-check-7f0fd8c5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from northline-webkit.northline-c86.workers.dev](https://www.zero.xyz/host/northline-webkit.northline-c86.workers.dev/llms.txt)