It's a web service that allows tech professionals to host their own code, share it with colleagues and jointly develop it in Open Source. To use the service, you need to register. Then you can start searching. You can search for specialists using three parameters: location, programming language, number of followers.
You can exclude unnecessary parameters from the request, and leave, for example, only the programming language. Don't forget to select the "Users" column in the list, as by default GitHub shows requests by the repository.