Tookie-OSINT is a free, open-source tool that scans hundreds of sites for a single username in seconds. This guide breaks down the real commands and flags, how the scanner actually works under the hood, and where it hits its limits once an investigation needs more than a list of matched profile URLs.

Finding out who owns a domain is one of the most fundamental skills in digital investigation — and in 2026, it is also one of the most challenging. With malicious domain registrations up 149% year over year and personal data increasingly hidden behind GDPR and RDAP privacy layers, a simple WHOIS lookup is rarely enough. This guide walks you through every method available, from basic public queries to advanced OSINT techniques, so you can identify the person or organization behind any domain with confidence.