Once you have more than one repository with sources you starting to search across all of them. You can use IDE and/or your favorite text editor to search across an open project. Usually, I use ‘grep’ to search in my ‘~/src’ directory.
It works pretty well when you have a few repos. But once you’ve got tens of them, it’s it’s time to find something convenient than ‘grep’. This way is good only if you prefer GUI rather than CLI.
Hound is an extremely fast source code search engine. It provides a simple web UI to search across your repositories. Hound works with different version control systems and public or private repositories. Unfortunately, it searches only for a master branch now, but there is a pull request to fix it. With a minimal feature set, it helps a lot to find anything you implemented in the past.