DNSdumpster.com is a FREE domain research tool that can discover hosts related to a domain. Finding visible hosts from the attackers perspective is an important part of the security assessment process.
Search across a half million git repos
Similar to grep.app - Search 75 billion lines of code from 40 million projects
Link: https://searchcode.com/
Search details about a domain.
https://cipher387.github.io/pastebinsearchengines/
Link: https://aadinternals.com/osint/
Search for buckets with the content of a specific keyword. Support AWS,Azure and DigitalOcean buckets.
https://buckets.grayhatwarfare.com