Assume you want find some python developers
You already know Douban, Zhihu and Airbnb have python as their main developing language. Just search their company name with https://github.com/search?q=zhihu&type=Users(Use zhihu as sample and The qualifier Users searches both users and orgs). Enter the organization and find the membershttps://github.com/orgs/zhihu/people
Enter one developer’s url(https://github.com/agentzh), find which organizations he in, and get other people.
Enter one good repo(https://github.com/openresty/lua-nginx-module), Get contributors in for this repo.
Just leave comments and mention him :)