ASN directory
ASN lookup: every autonomous system number, its operator and network type
An autonomous system number (ASN) is one organisation's piece of the routing table: a set of IP ranges announced to the rest of the internet under a single number, like AS15169 for Google or AS7922 for Comcast. Use this ASN directory to look up any network by number or operator name. Every address belongs to exactly one of them, so the ASN is the shortest honest answer to "who runs this address?". It is also the first thing that separates a customer at home from a server in a rack, because the two sit on different networks run by different companies for different reasons.
79,002 networks are in the directory. The 5,000 largest are listed here; search reaches all of them, and every one has its own page with the prefixes it announces and how the addresses classify.
Networks by type, of the 5,000 largest
The type is read from the operator's registered name and from the operator table the detection engine uses. 3,912 of these carry a name that says nothing either way, and those are left unclassified rather than guessed at.
Largest networks
Ranked by how many IPv4 addresses the operator announces, which is a better measure of reach than the prefix count beside it: a network can announce forty thousand small prefixes and still be smaller than one that announces a handful of large ones.
| ASN | Organisation | Type | Prefixes | IPv4 addresses |
|---|---|---|---|---|
| AS749 | DNIC-AS-00749 | Unclassified | 2,633 | 224,661,248 |
| AS16509 | AMAZON-02 | Hosting and cloud | 5,448 | 146,593,792 |
| AS4134 | Chinanet | Unclassified | 13,746 | 103,058,161 |
| AS7018 | ATT-INTERNET4 | Unclassified | 38,360 | 89,670,133 |
| AS7922 | COMCAST-7922 | Consumer ISP | 63,049 | 67,534,775 |
| AS8075 | MICROSOFT-CORP-MSN-AS-BLOCK | Hosting and cloud | 994 | 65,325,824 |
| AS4837 | CHINA UNICOM China169 Backbone | Consumer ISP | 1,789 | 57,138,685 |
| AS4766 | Korea Telecom | Consumer ISP | 5,318 | 46,368,763 |
| AS701 | UUNET | Unclassified | 22,246 | 40,222,468 |
| AS17676 | SoftBank Corp. | Mobile carrier | 194 | 35,909,886 |
| AS3320 | Deutsche Telekom AG | Consumer ISP | 1,688 | 34,062,068 |
| AS721 | DNIC-ASBLK-00721-00726 | Unclassified | 5,324 | 29,067,520 |
| AS4713 | NTT Communications Corporation | Consumer ISP | 263 | 28,691,710 |
| AS3356 | LEVEL3 | Unclassified | 4,819 | 28,070,654 |
| AS174 | COGENT-174 | Unclassified | 9,675 | 25,572,603 |
| AS3269 | TIM | Unclassified | 395 | 20,792,827 |
| AS3215 | Orange | Consumer ISP | 763 | 19,998,203 |
| AS9808 | China Mobile Communications Group Co., Ltd. | Mobile carrier | 3,603 | 18,727,680 |
| AS14618 | AMAZON-AES | Hosting and cloud | 1,011 | 18,132,480 |
| AS2516 | KDDI CORPORATION | Mobile carrier | 266 | 18,035,968 |
Showing 20 of the 5,000 networks in the committed snapshot. Search above to reach the rest.
Every page here is also an endpoint
No key, no signup. The same index answers a search or a single network, and the JSON is what these pages are rendered from.
curl https://ipscanner.io/v1/asn/directory/AS15169 curl "https://ipscanner.io/v1/asn/directory?q=comcast&limit=20" curl "https://ipscanner.io/v1/asn/directory?top=200&by=addresses"
What the ASN tells you, and what it does not
The number identifies who announces an address, which is a fact about ownership. It is strong evidence about what the address is used for and weak evidence about who is sitting behind it. A hosting ASN means the address is in somebody's infrastructure, so a request from it is a server rather than a person on a laptop, but plenty of legitimate traffic comes from servers. A consumer ISP means the opposite, and a VPN operator means the traffic was deliberately routed to hide where it came from.
Where an ASN cannot help at all is the residential proxy: an address that belongs to a real consumer ISP and is rented out anyway. That needs behaviour, not ownership, which is what the IP Detection API adds on top of the data in this directory.