ASN & IP-range explorer
Type an IP, a CIDR block, an AS number or a company name. Get the announcing network, its registry, its country, and every range it advertises to the internet.
- IPv4 and IPv6, with real longest-prefix matching
- The whole dataset ships with the page — nothing is sent anywhere
- One permanent page per network, not a disposable result URL
- Networks
- 37
- across 12 countries
- Announced prefixes
- 187
- 168 IPv4 · 19 IPv6
- IPv4 space covered
- 229M
- addresses inside the tracked blocks
- Cost to query
- Free
- no account, no rate limit
An IP resolves to the network announcing it. A CIDR block resolves to every announcement overlapping it. An AS number or a company name jumps straight to that network.
Every network we track
Sorted by AS number by default; the column headers re-sort it. Address totals count only the blocks listed on each network's page — real routing tables carry far more, so read them as a floor rather than a census.
37 networks · announced space only, not registry holdings
What the numbers actually mean
Four things worth understanding before you trust a lookup — including the two fields people most often read as facts when they are estimates.
What an AS number actually is
An autonomous system is one network under one routing policy. Comcast is an autonomous system. So is Cloudflare, so is a mid-sized university, so is any hosting company large enough to want its own transit. Each one is issued a number by a regional internet registry — ARIN in North America, RIPE NCC in Europe, APNIC in Asia-Pacific, LACNIC in Latin America, AFRINIC in Africa — and that number is how the rest of the internet refers to it.
There are roughly 100,000 autonomous systems with numbers assigned, and something like 75,000 of them visible in the global routing table at any moment. The gap is networks that hold a number but do not announce anything with it.
The number is the identity. The address ranges are what it does with that identity.
Prefixes, and why a /12 is bigger than a /20
A prefix is a block of addresses written as a network address followed by a slash and a number: 73.0.0.0/8, 104.16.0.0/13, 2606:4700::/32. The number after the slash counts the bits that are fixed. Everything left over is free to vary, so a smaller number means a larger block — a /8 holds 16,777,216 IPv4 addresses, a /24 holds 256.
Networks announce their prefixes over BGP, and every router on the internet builds a table of which neighbour to hand traffic to for each one. When two networks announce overlapping blocks, the more specific announcement wins: a /24 inside a /12 pulls traffic away from the /12 for those 256 addresses. That is longest-prefix match, and it is the single rule that makes the routing table work.
This tool shows every covering block, not just the winner, because a de-aggregated announcement is confusing until you can see the aggregate it came out of.
Why the ASN behind an address decides whether it works
Anti-bot systems rarely block individual addresses. Addresses are cheap and they rotate. What those systems block, throttle and challenge is address space — whole prefixes and whole autonomous systems, scored by what the traffic from them has historically looked like.
That scoring is why the same request succeeds from one address and fails from another that is numerically adjacent. An address on AS7922 arrives looking like a Comcast subscriber in Philadelphia, because that is what almost everything else in that block is. An address on AS24940 arrives looking like a German dedicated server, because that is what everything in that block is. No amount of header spoofing changes which prefix the packet came from.
So before blaming your fingerprint, check the range. It is the cheapest diagnostic available and it resolves a surprising share of "my scraper stopped working" cases outright.
How to read what this returns
The organisation is who registered the block, which is not always who is using it. Large carriers sub-allocate to business customers, and hosting resellers frequently announce space registered to somebody else entirely. Treat the org name as a strong hint rather than proof.
The country comes from the registry record, not from geolocation. A RIPE-registered block can be physically deployed anywhere, and anycast networks like Cloudflare answer from dozens of cities at once from a single prefix, so a country code on a CDN range tells you almost nothing about where the server sits.
The type — ISP, mobile, hosting, CDN, transit — is our classification of how the network is used rather than who owns it. It is the field that predicts blocking behaviour best, and the one no registry publishes.
Questions
What is an ASN?
An ASN, or autonomous system number, identifies a single network operating under one routing policy — an ISP, a hosting provider, a large enterprise. Regional internet registries assign the numbers, and networks use them to announce which IP address ranges they carry. Roughly 75,000 are visible in the global routing table at any moment.
How do I find the ASN for an IP address?
Paste the address into the search box above. The explorer matches it against every announced prefix in the dataset and returns the announcing network, longest-prefix match first. That is the same rule real routers use to pick a route.
Is this the same as a GeoIP lookup?
No. This reads routing and registry data, which tells you which network announces an address. GeoIP databases guess at a physical location, and they are frequently wrong — especially on mobile carriers, anycast ranges and recently transferred blocks. The ASN is a fact; the city is an estimate.
Why does an IP show more than one prefix?
Networks often announce a large aggregate and one or more smaller blocks inside it, usually for traffic engineering. Every covering block is listed here, most specific first. On the real internet only the most specific one carries traffic.
Does the ASN affect whether a proxy gets blocked?
Substantially. Anti-bot systems score address space rather than individual addresses, so an IP on a hosting ASN starts from a much worse position than one on a residential ISP — before any request is even made. Checking the ASN behind an address is the fastest way to explain why an otherwise identical request succeeds from one exit and fails from another.
Where does this data come from, and how complete is it?
AS numbers, organisations, countries and registries are public routing and registry facts. The prefix lists in this build are a representative subset rather than a full routing table dump, so address totals are a floor rather than a census. Anything the dataset does not cover is reported as not found instead of guessed at.
Is there a rate limit or a signup?
Neither. The whole dataset ships with the page and every lookup runs in your browser, so nothing is sent anywhere and there is nothing to sign up for.
We sell on four of these networks
Our dedicated ISP addresses sit on Comcast, AT&T, Frontier and Windstream subnets. Verify that the way you would verify anyone else's claim — take an address we issue, paste it into the box above, and read which network announces it. The trial is $1.
- AS5650 Frontier Communications of America
- AS7018 AT&T Services
- AS7029 Windstream Communications
- AS7922 Comcast Cable Communications
Testing a whole list rather than one address? The bulk proxy checker reports exit country, ASN and anonymity for up to 500 proxies at once.