Reverse IP LookupFree Reverse IP Domain Checker

A reverse IP lookup takes one IP address and lists the domain names that point to it. The Kwebby reverse IP domain checker runs this lookup for you: enter a domain or an IP address, click Lookup, and read the hostnames that its data provider has seen on that address. This guide explains what the list shows, where it can mislead you, and how to use it for hosting, security and email checks. More server tools live in our Free Developer Tools.

Key Takeaways

• The tool accepts a domain or an IP address and returns the resolved IP, a Domains Found count and a list of hostnames.
• The data comes from the HackerTarget free API, which builds its records from web crawls, Bing, Common Crawl, Certificate Transparency logs and scans.io.
• The list includes subdomains and can run to hundreds of names. In our tests, kwebby.com returned 470 and example.com returned 273.
• Sites behind a CDN or proxy share addresses with many unrelated sites, so a long list does not prove shared hosting.
• A reverse IP lookup, which lists domains on an address, differs from reverse DNS, which returns one hostname from a PTR record.
• The tool is free and needs no account.

What Is the Kwebby Reverse IP Domain Checker?

The Kwebby Reverse IP Domain Checker is a free web tool that finds the domains and hostnames linked to an IP address. You can type an IP address directly, or type a domain and let the tool resolve its address first.

Search results for this topic mix two different checks. Reverse DNS asks which hostname belongs to an IP address and answers from a PTR record. Cloudflare explains that PTR records store the address with its segments reversed and add .in-addr.arpa, so 192.0.2.1 becomes 1.2.0.192.in-addr.arpa. A reverse IP lookup asks a wider question: which domains point to this address? The Kwebby tool runs that second check.

Key Features and How It Works

The tool has one input box, one button and a result area that appears below them.

One Box for a Domain or an IP

The box shows the example text "e.g. example.com or 1.2.3.4". Type a domain or an IP address, then click Lookup or press Enter. While the request runs, the button reads "Looking up..." and a spinner shows the message "Performing reverse IP lookup via HackerTarget...". The button stays disabled until you type something.

Resolved IP and Domains Found

The result starts with two figures. Resolved IP shows the address the lookup used. Domains Found shows how many names came back.

On 4 October 2026, a test on kwebby.com resolved to 172.64.80.1 and returned 470 names. A test on example.com resolved to 104.20.23.154 and returned 273. A test on the IP address 8.8.8.8 returned exactly 500 names, which looks like a cap, so treat very long lists as partial.

A Filterable List of Hostnames

When the count is above zero, a Filter domains... box appears above a scrolling list. Type part of a name to narrow the list, and the message "No domains match filter" appears if nothing fits. Each hostname links to its https address and opens in a new tab.

The entries are hostnames, so the list includes subdomains, such as admin.isilive.net in the kwebby.com result.

A Note From the Data Provider

An amber note appears when the provider sends a message. If the provider's daily free quota is used up, the note says so and the count shows zero; try again the next day. If the provider has no other domains for the address, the note says that instead. An address that is not a valid domain or IPv4 address gets a red input error, and each visitor can run five lookups per minute.

Where the Data Comes From

The footer names HackerTarget as the data source and notes that the list can be incomplete. HackerTarget says the bulk of its reverse IP data comes from its crawls of the Alexa Top 1 Million sites, Bing, Common Crawl, Certificate Transparency and the scans.io project.

That means the list reflects what those sources have seen. It is not a live query of the web server, so a domain can be missing, and an old name can linger after a site moves.

Why Checking Domains on an IP Matters

One IP address often serves many websites. The HTTP Host header makes this possible: MDN describes the Host header as carrying the domain name of the server for virtual hosting, so the server reads it to pick the right site. An address alone does not name a single site.

That is why the list is worth reading. It shows who else sits on an address, whether a hosting plan behaves as sold, and whether a server holds sites you did not expect. It also helps when you review a mail server, because blocklists work on IP addresses.

How to Use the Reverse IP Domain Checker

1. Open the tool and click the box that reads "e.g. example.com or 1.2.3.4".
2. Type a domain or an IP address.
3. Click Lookup, or press Enter. The button reads "Looking up..." while the request runs.
4. Read Resolved IP and Domains Found at the top of the result.
5. Type part of a name into Filter domains... to narrow the list.
6. Click a hostname to open it in a new tab.

If a red message appears, check the address for typos. If the amber note mentions the daily quota, try again the next day.

Best Practices

Read the Count Against Your Hosting Type

A site behind a CDN or proxy returns the shared addresses of that service. Both kwebby.com and example.com send a server header of "cloudflare", and both returned hundreds of unrelated names. A long list for such a site shows the shared edge address, not your neighbors on a web server. Use the Domain Hosting Checker to see who hosts a site.

Treat the List as a Lead

The data lags behind live DNS. Confirm important findings by looking up the A record for each name with Find DNS Records before you act on them.

Check the Address for Spam Listings

If a server sends mail, run its address through the Blacklist Lookup. A bad neighbor on a shared address can matter for mail, because blocklists list addresses.

Look Beyond One Address

Neighbors can sit in the same network block. The Class C IP Checker groups many domains by network block and shows which ones share it.

Do Not Read Ownership Into a Shared IP

Two domains on one address do not prove the same owner. Many unrelated sites share hosting. Check registration data with the WHOIS Checker before you draw a link between sites.

Common Use Cases

• Hosting audits. List what an address serves before you migrate a site or cancel a plan.
• Dedicated IP checks. Look for unexpected names, then confirm with your host, because the list can be incomplete.
• Security research. Find forgotten subdomains and test sites that share a server with a main domain.
• Mail reviews. Check which names share the address of a mail server before you test it for blocklists.
• Competitor research. See which sites share an address with a competitor, and treat the result as a clue, not a fact.
• IP resolution checks. Compare the Resolved IP with the addresses from Domain Into IP.

Related Kwebby Tools

• Domain Hosting Checker shows where a website is hosted.
• Domain Into IP finds the IP addresses behind a domain.
• Class C IP Checker groups domains by network block.
• Blacklist Lookup checks an IP address against spam lists.
• Find DNS Records shows the DNS records of a domain.
• WHOIS Checker shows registration details for a domain.

Final Thoughts

A reverse IP lookup answers one narrow question: which names has a data provider seen on this address? A CDN or a result cap can change what the count means, so read every answer with those limits in mind. Enter your own domain now, note the Resolved IP and the count, and then run the Domain Hosting Checker to see who hosts it.