ASN Lookup APIs
ASN lookups tell you which network an IP address belongs to. BigDataCloud's Network Engineering API goes deepest, with BGP prefix data and Tor exit-node detection, and HackerTarget pairs ASN lookups with DNS, WHOIS and subnet tools as plain text. For a quick answer without a key, GeoJS, ipapi.co and IPQuery return the ASN alongside geolocation, while Host.io ties IPs and ASNs to domain data.
| API | Pricing | Auth | Format | Free tier | Status |
|---|---|---|---|---|---|
BigDataCloud's Network Engineering APIASN details, BGP prefix data, IP-to-network lookups and Tor exit-node detection for network engineering. Location & Mapping › IP Geolocation | Freemium | API key | JSON | 100–1k/day | Untested |
Country.isLooks up a visitor's country (and optionally city/ASN) from their IP address. Location & Mapping › IP Geolocation | Free | None | JSON | Unlimited | Live |
GeoJSFree IP geolocation lookup returning country, city, coordinates and ASN, no key required. Location & Mapping › IP Geolocation | Free | None | JSON | Unlimited | Live |
HackerTarget IP Tools APIASN, DNS, reverse DNS/IP, WHOIS, GeoIP, HTTP header and subnet lookups for any IP or domain as plain text. Developer Tools › WHOIS & DNS | Freemium | None | CSV | <100/day | Live |
Host.ioDNS records, backlinks, IP/ASN and related-domain data across 600M+ registered domains. Developer Tools › WHOIS & DNS | Freemium | API key | JSON | <100/day | Live |
ip.appReturns caller's IP, ASN, geolocation, timezone, user-agent and basic bot/security signals. Location & Mapping › IP Geolocation | Free | None | JSON | Unlimited | Live |
Ip2GeoConverts an IPv4/IPv6 address into country, city, coordinates, timezone, currency and ASN data. Location & Mapping › IP Geolocation | Freemium | API key | JSON | <100/day | Live |
ipapi.coLooks up city, region, country, coordinates, timezone, and ASN for any IPv4/IPv6 address. Location & Mapping › IP Geolocation | Freemium | None | JSON | 100–1k/day | Live |
ipgeolocation.ioIP-to-location, timezone, ASN, currency, and (paid) security/company data for any IP address. Location & Mapping › IP Geolocation | Freemium | API key | JSON | 100–1k/day | Live |
ipgeolocationapiIP-to-location lookup with ASN, timezone, currency and (paid) VPN/proxy threat detection, no key for basics. Location & Mapping › IP Geolocation | Freemium | API key | JSON | 1k–10k/day | Live |
IPinfoMaps an IPv4 or IPv6 address to country and ASN free; paid tiers add city, VPN/proxy and carrier data Location & Mapping › IP Geolocation | Freemium | API key | JSON | Unlimited | Live |
IPLocateIP geolocation plus ASN, hosting, company and privacy/threat data (VPN, proxy, Tor detection) for any IP. Location & Mapping › IP Geolocation | Freemium | API key | JSON | 1k–10k/day | Live |
IPQueryFree keyless IP lookup: geolocation, ISP/ASN, and VPN, Tor, proxy and datacenter risk flags. Location & Mapping › IP Geolocation | Free | None | JSON | Unlimited | Live |
MyIPRightNowReturns the caller's public IP, ASN, ISP, geolocation and timezone as JSON with no key needed. Location & Mapping › IP Geolocation | Free | None | JSON | Unlimited | Live |
Proweblook IP CheckerEdge-hosted IP geolocation returning country, city, ASN, ISP, timezone and VPN/proxy risk flags. Location & Mapping › IP Geolocation | Freemium | API key | JSON | 100–1k/day | Live |
The IP APIIP geolocation, ASN/WHOIS lookup and VPN/datacenter/bogon detection for IPv4 and IPv6. Location & Mapping › IP Geolocation | Freemium | API key | JSON | 1k–10k/day | Degraded |
BigDataCloud's Network Engineering APIFreemiumUntested
ASN details, BGP prefix data, IP-to-network lookups and Tor exit-node detection for network engineering.
API key · JSON
100–1k/day
llms.txt
Country.isFreeLive
Looks up a visitor's country (and optionally city/ASN) from their IP address.
None · JSON
Unlimited
llms.txt
GeoJSFreeLive
Free IP geolocation lookup returning country, city, coordinates and ASN, no key required.
None · JSON
Unlimited
no machine-readable spec
HackerTarget IP Tools APIFreemiumLive
ASN, DNS, reverse DNS/IP, WHOIS, GeoIP, HTTP header and subnet lookups for any IP or domain as plain text.
None · CSV
<100/day
no machine-readable spec
Host.ioFreemiumLive
DNS records, backlinks, IP/ASN and related-domain data across 600M+ registered domains.
API key · JSON
<100/day
no machine-readable spec
ip.appFreeLive
Returns caller's IP, ASN, geolocation, timezone, user-agent and basic bot/security signals.
None · JSON
Unlimited
OpenAPI spec · MCP server · llms.txt
Ip2GeoFreemiumLive
Converts an IPv4/IPv6 address into country, city, coordinates, timezone, currency and ASN data.
API key · JSON
<100/day
llms.txt
ipapi.coFreemiumLive
Looks up city, region, country, coordinates, timezone, and ASN for any IPv4/IPv6 address.
None · JSON
100–1k/day
no machine-readable spec
ipgeolocation.ioFreemiumLive
IP-to-location, timezone, ASN, currency, and (paid) security/company data for any IP address.
API key · JSON
100–1k/day
llms.txt
ipgeolocationapiFreemiumLive
IP-to-location lookup with ASN, timezone, currency and (paid) VPN/proxy threat detection, no key for basics.
API key · JSON
1k–10k/day
OpenAPI spec
IPinfoFreemiumLive
Maps an IPv4 or IPv6 address to country and ASN free; paid tiers add city, VPN/proxy and carrier data
API key · JSON
Unlimited
no machine-readable spec
IPLocateFreemiumLive
IP geolocation plus ASN, hosting, company and privacy/threat data (VPN, proxy, Tor detection) for any IP.
API key · JSON
1k–10k/day
llms.txt
IPQueryFreeLive
Free keyless IP lookup: geolocation, ISP/ASN, and VPN, Tor, proxy and datacenter risk flags.
None · JSON
Unlimited
no machine-readable spec
MyIPRightNowFreeLive
Returns the caller's public IP, ASN, ISP, geolocation and timezone as JSON with no key needed.
None · JSON
Unlimited
no machine-readable spec
Proweblook IP CheckerFreemiumLive
Edge-hosted IP geolocation returning country, city, ASN, ISP, timezone and VPN/proxy risk flags.
API key · JSON
100–1k/day
OpenAPI spec · llms.txt
The IP APIFreemiumDegraded
IP geolocation, ASN/WHOIS lookup and VPN/datacenter/bogon detection for IPv4 and IPv6.
API key · JSON
1k–10k/day
llms.txt
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Choosing an ASN Lookup API
Is there a free ASN Lookup API?
Yes. GeoJS, Country.is, ip.app, IPQuery and MyIPRightNow are free to use, and IPinfo, HackerTarget IP Tools API, BigDataCloud's Network Engineering API, Host.io, Ip2Geo and 6 others have a free tier alongside paid plans.
Which ASN Lookup APIs work without an API key?
HackerTarget IP Tools API, GeoJS, Country.is, ip.app, ipapi.co and 2 others need no key or sign-up, so you can try them with a plain request.
Can I call an ASN Lookup API from front-end JavaScript?
HackerTarget IP Tools API, GeoJS, Country.is, ip.app, ipapi.co and 2 others allow cross-origin requests and need no key, so they work straight from the browser. For the others, call them from your server so your key stays private.
Can I use ASN Lookup APIs in a commercial project?
IPinfo, BigDataCloud's Network Engineering API, Country.is and ipgeolocationapi permit commercial use. ipapi.co and ipgeolocation.io restrict it, for example to non-commercial or attributed use, so read the terms first.
Which ASN Lookup APIs work with AI agents?
ip.app has both an MCP server and an OpenAPI spec. ipgeolocationapi and Proweblook IP Checker publish an OpenAPI spec for generating clients and tools.
Broader: IP Geolocation APIs · Location & Mapping APIs
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