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ZeroWorker Web Action Preflight API
x402
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 2026-10-14).
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.
Price / call$0.002
Success—
StatusUnknown
How this service works
Avoid unnecessary browser launches with a lightweight preflight for AI agents. ZeroWorker inspects public pages before browser automation and returns static forms, field constraints, CAPTCHA/SPA signals, DNS/public-network safety checks, and a 3-state routing verdict: http_candidate, browser_likely, or undetermined. Use it to choose direct HTTP or escalate to a browser. No API key required. $0.003 USDC per successful request via x402 on Base Mainnet.
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.
Example use cases
Pre-check login form before automation
“Before I automate the login on https://acme.com/login, can you inspect the page and tell me what the form fields are called, whether there's a CAPTCHA, and if a full browser session will be required?”
Discover checkout form fields
“I want to know what input fields and options are on the checkout page at https://shop.example.com/checkout before I build a script — can you pull the form structure and any constraints?”
DNS and safety check before web action
“Can you run a preflight on https://somethirdpartysite.com/apply and let me know if the domain passes DNS safety checks, what forms are on the page, and whether it looks like a JavaScript-heavy SPA?”
Technical details
Endpoint
POSThttps://zeroworker-web-action-api.zeroworker-lab.workers.dev/v1/preflight?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Absolute public HTTP(S) URL to inspect. Literal IPs, localhost/local hostnames, credentials, and non-standard ports are rejected. |
| access | object |
Tags
x402
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