OWASP Amass - An advanced open source tool to help information security professionals perform network mapping of attack surfaces and external asset discovery using open source information gathering and active reconnaissance techniques!
SIREN.io - Siren is an investigative intelligence platform.
SpiderFoot - Open source intelligence (OSINT) automation tool.
DataWalk - DataWalk is a software platform to connect numerous large data sets, both external and internal, into a single repository for fast visual analysis.
Subfinder - Subfinder is a subdomain discovery tool that discovers valid subdomains for websites. Designed as a passive framework to be useful for bug bounties and safe for penetration testing. - GitHub - proj...
Netglub - Netglub, the really open source information gathering solution.