Findomain
Fast open source tool for discovering and monitoring domain subdomains
...It focuses on speed and reliability by using Certificate Transparency logs and multiple well tested public APIs instead of relying solely on brute force scanning techniques. By querying multiple passive data sources in parallel, the tool can identify a large number of subdomains within a short time, making it useful for security researchers, penetration testers, and bug bounty hunters. Findomain aggregates information from various online services to provide a comprehensive list of discovered subdomains without directly attacking the target infrastructure. ...