# ZeroWorker Web Action Preflight API

> ZeroWorker Web Action Preflight API is a paid API for AI agents from zeroworker-web-action-api.zeroworker-lab.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-18).

Inspects a public web page before launching a browser session, returning HTML forms, field metadata, CAPTCHA/SPA signals, DNS safety results, and a browser-required heuristic as structured JSON.

## Facts

- Endpoint: POST https://zeroworker-web-action-api.zeroworker-lab.workers.dev/v1/preflight?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/zeroworker-web-action-preflight-api-c0ce5a15
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vIxD4VPK0PpvMXctERtu_

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 zeroworker-web-action-preflight-api-c0ce5a15 -d '<json body>'
```

Example prompt: Before we start the browser session, can you preflight the page at https://example.com/signup and tell me what forms are on it, whether it has a CAPTCHA, if it's a SPA, and whether a real browser will be needed?

## When to prefer this

Choose this endpoint when you need a lightweight, deterministic inspection of a public web page before committing to a full browser automation session. It is ideal for agents that want to discover form structure, field names, and constraints without spinning up a headless browser, or when you need to quickly assess whether a CAPTCHA or SPA will block simple HTTP-based automation. Prefer it over direct scraping when you need structured JSON output about forms rather than raw HTML, and over full browser sessions when cost and latency matter and the page may be statically renderable.

## Known failure modes

- URL is not publicly accessible or returns a non-200 status — preflight may return incomplete or empty form data
- Page is fully JavaScript-rendered at load time — static HTML extraction may miss dynamically injected forms
- DNS safety check failure — endpoint may flag or refuse the target URL
- Network timeout fetching the target page — request returns an error
- Malformed or non-HTTP URL provided — validation error returned
- CAPTCHA detection is heuristic and may produce false positives or negatives for novel CAPTCHA implementations

## How this service works

Inspect public static HTML before browser automation: forms, field constraints, CAPTCHA/SPA/JS signals, DNS safety, and a 3-state routing verdict: http_candidate, browser_likely, or undetermined. No action execution or API key required. When enabled, try 10 successful live calls free once across HTTP/MCP; then $0.002 USDC per successful paid request via x402 on Base Mainnet. Starter policy: /anonymous-access-policy.

## Output

A machine-readable JSON response containing: all static HTML forms found on the page with their action URLs; each form field's label, name, type, current value, available options, and constraints; signals indicating whether a CAPTCHA is present; whether the page is a single-page application (SPA); DNS and public-network safety results; and a boolean heuristic indicating whether a full browser session is likely required to interact with the page.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Absolute public HTTP(S) URL to inspect. Literal IPs, localhost/local hostnames, credentials, and non-standard ports are rejected."
  },
  "access": {
   "type": "object",
   "properties": {
    "clientToken": {
     "type": "string",
     "pattern": "^zw_a_[a-f0-9]{64}$",
     "description": "Saved anonymous starter token. Omit on the first live request."
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/zeroworker-web-action-preflight-api-c0ce5a15/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from zeroworker-web-action-api.zeroworker-lab.workers.dev](https://www.zero.xyz/host/zeroworker-web-action-api.zeroworker-lab.workers.dev/llms.txt)