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how.is URL Preflight Safety Check
x402
how.is URL Preflight Safety Check is a paid API for AI agents from how.is, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-31).
Runs a multi-signal safety pre-flight check on a URL before an agent fetches, reads, signs in, or pays — returning a verdict, risk score, robots.txt compliance, HTTPS validity, blocklist hits, domain age, lookalike detection, and x402 pricing.
Price / call$0.005
Success—
StatusUnknown
How this service works
Check whether a URL is safe to fetch, read, sign in to or pay before you do: domain age, look-alike, blocklists, HTTPS, robots.txt for your agent and the site's own x402 price.
Output
A JSON object containing: a top-level verdict (likely_safe / caution / high_risk / inconclusive), numeric risk_score, per-action safe_to flags (fetch / read / sign_in / pay each as yes/caution/no/unknown), per-action reasons with explanations, domain_age_days, newborn flag, lookalike flag, https_valid, robots.txt compliance and token for the given user agent, HTTP status and redirect chain, x402 payment offers (price_usd, network, pay_to) if present, bot policy details, and a list of checks that were not performed. Also includes a payment receipt confirming the $0.005 USDC charge.
Example use cases
Safe-to-pay check before checkout
“I'm about to send payment to https://shop.nikke-shoes.com — before you do anything, check if that URL is safe to pay on, look for lookalike or phishing signals, and tell me the risk verdict.”
Agent fetch permission verification
“Check whether https://data.competitor-tracker.io is safe for you to fetch with your GPTBot user agent — I need to know if robots.txt allows it and whether the domain has any blocklist or newborn-domain red flags.”
Pre-login safety screening
“Before I log in to https://mybank-secure-portal.net, run a safety preflight on that URL and tell me if it's really safe to sign in — domain age, HTTPS validity, lookalike warnings, and the overall risk score.”
Technical details
Endpoint
POSThttps://how.is/v1/url/preflight?utm_source=zero.xyzWhen to prefer
Use this endpoint whenever an AI agent is about to interact with an unknown or user-supplied URL — especially before fetching content, following redirects, authenticating, or making payments. It is the right choice when you need a single consolidated safety signal rather than calling separate blocklist, WHOIS, HTTPS, and robots.txt services individually. Particularly valuable in agentic workflows where acting on a malicious URL could cause financial loss or security compromise.
Side effects
- Invalid or malformed URL returns a 4xx error
- Private/localhost URLs may be rejected or return inconclusive
- Some signals (blocklist, domain age) may be unavailable, listed in not_checked[]
- robots.txt unreachable results in unknown robots status
- DNS resolution failure for the target domain yields inconclusive verdict
- Payment failure (insufficient x402 balance) prevents the check from completing
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| ua | string | The user agent you will fetch with; robots.txt and our bot policy are judged for it. Defaults to the User-Agent of this request. |
| url | string | The http(s) URL you are about to fetch |
Output
Schema · Response
{
"type": "json",
"example": {
"data": {
"_shape": "data: verdict (likely_safe/caution/high_risk/inconclusive), risk_score, safe_to{fetch,read,sign_in,pay} each yes/caution/no/unknown, actions{...: {answer, why}}, reasons[{risk, why}], domain_age_days, newborn, lookalike, https_valid, robots{allowed, token, status}, http{status, content_type, redirects}, x402{offers[{price_usd, network, pay_to}]}, bot_policy, not_checked[]."
},
"result": "URL pre-flight for the requested subject",
"receipt": {
"rail": "x402",
"tool": "preflight",
"charge_usd": 0.005,
"settlement_tx": "0x…"
}
}
}Tags
x402
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