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SiteCheck Web Intel – Cymru ASN Lookup
x402
SiteCheck Web Intel – Cymru ASN Lookup is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).
Resolves an IPv4 address to its origin AS number, BGP prefix, country, registry, and allocation date using Team Cymru's IP-to-ASN DNS service.
Price / call$0.002
Success—
StatusUnknown
How this service works
Maps an IPv4 address to its origin AS number, the BGP prefix that covers it, the country, the registry and the allocation date, using Team Cymru's public IP-to-ASN DNS service. Returns no origin when Cymru has no mapping for the address.
Output
Returns the origin AS number (e.g. AS15169), the BGP CIDR prefix covering the IP (e.g. 8.8.8.0/24), the two-letter country code, the RIR name (ARIN, RIPE, APNIC, etc.), and the allocation date. Returns no origin if Team Cymru has no mapping for the address.
Example use cases
Investigate suspicious inbound traffic
“I'm seeing a lot of traffic from 185.220.101.55 — can you tell me which autonomous system and country that IP belongs to, and when that prefix was allocated?”
Enrich threat intelligence report
“I need to enrich my threat report: look up the origin AS number, BGP prefix, and RIR registry for the IP 45.142.212.100.”
Network troubleshooting for ops team
“We're debugging a routing issue — can you find which ASN and BGP prefix covers 1.1.1.1, and which regional internet registry allocated it?”
Technical details
Endpoint
GEThttps://api.webintel-api.workers.dev/api/security/cymru-asn-lookup?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need authoritative BGP routing context for an IPv4 address — specifically the ASN, prefix, RIR, and allocation date — sourced from Team Cymru's well-known passive DNS dataset. Prefer this over generic WHOIS or geolocation APIs when you need routing-layer data rather than registrant contact details or city-level geolocation.
Side effects
- IP not found in Cymru's database — returns no origin/empty mapping
- Invalid IPv4 address format — likely 400 or validation error
- Private/reserved IP ranges (RFC1918, loopback) may return no result
- Cymru DNS service temporarily unavailable — upstream timeout
- Rate limiting or payment failure due to x402 protocol issues
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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