Sherlock, a powerful command line tool provided by Sherlock Project, can be used to find usernames across many social networks.
Sherlock supports 369 social media network sites.
It requires Python 3.6 or higher and works on macOS, Linux and Windows.
Sherlock is originally created by Siddharth Dushantha, but it now has dozens of contributors who keep it updated.
License
MIT © Sherlock Project