About LookupOwl
Free tools for seeing how the internet is set up, for people, scripts and AI assistants alike.
- No accounts, keys or captchas
- Privacy first: we log as little as we can
- Honest results, with sources and times
- Built for AI agents too
What LookupOwl is
LookupOwl is a collection of free tools for looking at how the internet is set up: who registered a domain, where a hostname points, who owns an IP address, whether a certificate is about to expire, whether an email domain is protected against forgery. Every tool works three ways: as a web page for people, as a REST API for scripts, and as an MCP tool for AI assistants.
We started from a simple frustration. Most free network tools make you solve a captcha, click through ads, sign up for a trial or accept that the results are a guess. They are also hard for software to use. LookupOwl aims to be the opposite: fast, honest about what it knows, readable by people and AI agents alike, and free of accounts.
How we work
- No accounts, no keys, no captchas. You should be able to look something up, or call the API, without telling anyone who you are.
- Privacy first. No accounts, no ads, and we log as little as we can to run the service safely. We do count visits with Google Analytics, and the privacy policy spells out exactly what is logged and what is measured.
- Honest results. If a registry doesn't answer, we say we couldn't check instead of guessing. Results show where the data came from and when.
- Plain English first. Dates, status codes and errors are explained, with the standards cited so you can read further.
- Kind to the systems we ask. We cache, pace our requests and identify ourselves, so registries, resolvers and websites aren't overloaded on your behalf.
- Built for agents too. Each tool has typed inputs and outputs, a clear description for AI models, and a link back to a page a person can read.
Where the data comes from
We don't keep a database of domains or people. Almost everything is fetched live from the authoritative source when you ask, then cached briefly:
| Data | Source |
|---|---|
| Domain registration | RDAP servers run by registries and registrars, found through the IANA bootstrap registry, with the registry's WHOIS server as a fallback |
| IP address and AS number registration | RDAP servers of the five regional internet registries (ARIN, RIPE NCC, APNIC, LACNIC, AFRINIC) |
| DNS records | Public DNS resolvers and the authoritative nameservers of the domain you query |
| HTTP headers and redirects | A live request from our servers to the public website you enter |
| TLS certificates | A live TLS connection from our servers to the host you enter |
| Security headers | A live request from our servers to the public website you enter, the same one the HTTP headers checker makes |
| IP location and network owner | The free DB-IP Lite databases (CC BY 4.0), downloaded each month and read from our own server. IP geolocation by DB-IP |
| Who hosts a website | DNS answers, the DB-IP Lite network data, our own list of hosting providers and, when those are not enough, at most one request to the site |
| Mail blocklists | Public DNS blocklists such as Spamhaus and SpamCop, asked by DNS query for the IP address or domain you enter |
| MAC address vendors | The IEEE registries, kept as a copy on our own server |
| Status codes and standards | The IETF RFCs and IANA registries, written up in our own words |
Registration data is public information published under each registry's own terms. We don't scrape, sell or enrich it.
For developers and AI agents
- The MCP server is at
https://lookupowl.com/mcp(Streamable HTTP, no sign-in). The guide shows how to connect your assistant. - The REST API is described by an OpenAPI 3.1 document at
/api/openapi.json, and the tool catalogue is at/api/v1/tools. /llms.txtand/llms-full.txtdescribe every tool for language models, and each tool has a Markdown page.- The rate limits and fair-use rules are in the terms.
Say hello
Found a bug, a wrong answer, or something we could explain better? We'd genuinely love to hear it. For security reports, abuse complaints about traffic from our servers, data-correction requests or anything else, use the contact details in our security.txt file at /.well-known/security.txt. We read everything, and we would rather hear about a problem than have you work around it.
If a website, DNS operator or network owner would like us to stop querying it, tell us through the same address and we will add it to our opt-out list.