Open source intelligence websites for checking companies and domains
Free sites for domain, certificate, page history and company records, and AyeWatch for alerts when a competitor's pages change.
By ClaudeGPT Si Newsroom, Editorial team··3 min read
The open source intelligence websites that help most when you are sizing up a company or a domain are free: ICANN Lookup for registration data, crt.sh for certificates, the Wayback Machine for page history, urlscan.io for what a page loads, and SEC EDGAR and OpenCorporates for company records. To keep up with those sources after the first look, AyeWatch watches pages and topics and alerts you when they change.
Why marketers and SEO teams use OSINT
Competitor research is OSINT with a marketing goal. Before you plan content against a rival, it helps to know which subdomains they run, how their pricing page has changed, what their filings say about new markets, and which products their job posts hint at. All of it is public if you know where to look.
Websites grouped by the question they answer
| Question | Website | What you get |
|---|---|---|
| How has this page changed over time? | Wayback Machine | Archived captures by date |
| How is the domain registered? | ICANN Lookup | Current registration data |
| Which subdomains exist? | crt.sh | Certificates from public CT logs |
| What does this page load and call? | urlscan.io | A recorded visit to the URL |
| Who is behind the company? | OpenCorporates | Registry records from 140+ jurisdictions |
| What does a public company disclose? | SEC EDGAR | Filings and full-text search |
| What changes next? | AyeWatch | Alerts with a summary and sources |
Domain and site research
ICANN Lookup is ICANN's own tool for the current registration data of a domain name. crt.sh, run by Sectigo, searches Certificate Transparency logs by domain or organization name, and the list of certificates is a fast way to spot staging sites, help centers and regional subdomains. urlscan.io describes itself as a sandbox for the web: it visits a URL and records what the page loads, which helps you see the scripts and third-party services behind a competitor's landing page. The Wayback Machine lets you compare an old capture of a page with today's version, so you can see when a headline, a plan name or a price moved.
Company records
OpenCorporates gathers company data from official registries in more than 140 jurisdictions and lets you search by company name or by officer. For US public companies, SEC EDGAR is free to use, and its full-text search covers more than 20 years of filings, which makes it easy to find where a product or market first shows up in an annual report.
Watching instead of revisiting: AyeWatch
Every site above shows how things stand today, and competitor research goes stale quickly. A pricing table gets rewritten, a careers page adds a new team, a product is renamed. AyeWatch handles the follow-up. Paste a competitor's pricing page or changelog URL, or describe a topic such as a rival's launches and partnerships, and it sends a short summary with source links when something meaningful changes. It can also follow the public X accounts and subreddits where a brand gets discussed. Paid plans start at $9 a month, and there is a free preview to try it first.
Directories to bookmark
Bellingcat's Online Investigation Toolkit sorts tools into categories such as websites, companies and finance, social media and archiving. OSINT Framework is a separate directory focused on free resources, with marks for tools that need registration or a local install.
Ground rules
Use public records, respect each site's terms, and keep the research on companies, brands and websites. None of these sites should be used to profile private people.
When a heavier tool fits better
For a full technical inventory of one domain, a local scanner such as SpiderFoot runs many lookups at once and is worth the install. For following a handful of competitor pages over months, an AyeWatch monitor on each page saves the repeat visits.