Your ISP is the company that provides your internet connection and owns the block of addresses your connection sits in. It is detected from your IP address and shown at the top of this page.

What is an ASN number?

An Autonomous System Number identifies a network that routes traffic independently on the internet. Every ISP has at least one, and it is the most precise way to name the network you are connected through.

Why does my ISP show as a different company?

Smaller providers often resell capacity from a larger carrier, so the registry record names the carrier. Mobile and VPN connections commonly show the parent network rather than the brand you pay.

What Is My ISP? — Find Your Internet Provider and ASN

How your ISP is identified

Nothing about your provider is guessed. Regional internet registries — ARIN, RIPE NCC, APNIC, LACNIC and AFRINIC — publish which organisation holds every block of addresses. Your IP address falls inside one of those blocks, and the record names the holder.

This is why the provider and ASN shown above are reliable in a way that city-level geolocation never is. One comes from a published registration; the other is an estimate.

What an ASN number actually is

An Autonomous System Number identifies a network that makes its own routing decisions on the internet. Written as AS15169 or similar, it is the most precise way to name the network you are connected through.

Every ISP has at least one; large carriers hold dozens. The number matters more than the name in practice, because company names change with mergers while the ASN keeps routing traffic under the same identifier. When a firewall rule, an abuse report or a CDN configuration needs to describe a network, it uses the ASN.

Why the name might surprise you

Three common reasons the ISP shown is not the company you pay:

Resellers. Smaller providers buy capacity wholesale, so the addresses are registered to the carrier underneath.
Mergers. Registry records often keep an acquired company's name for years after the brand disappears.
VPNs and proxies. If a tunnel is active, you will see the hosting company behind the VPN server rather than your own provider. That is the tunnel working.

Mobile connections are the most confusing of all, because traffic frequently exits through a regional gateway registered to a parent network in another city.

What your ISP can see

More than any website does, and it is worth being clear about. Your provider assigns your address and carries every packet, so they can see which servers you connect to and when, how much data you move, and — through DNS queries, unless you have changed resolver — which domain names you look up.

What they cannot read is the content of anything sent over HTTPS, which is now nearly all web traffic. They see that you connected to a site, not what you did there. A VPN removes even the first part, at the cost of moving that visibility to the VPN company instead.

Using this information

Support calls. Quoting your public IP address and ASN gets you past first-line scripts quickly.
Checking a VPN. If the ISP above is your VPN provider's host rather than your own, the tunnel is carrying traffic.
Diagnosing blocks. Some services block entire ASNs associated with data centres. Knowing yours explains a lot of otherwise baffling refusals.
Comparing performance. Run a speed test and you have both the network name and its real throughput in one place.