Grep is a took that has been built by the team over at Vercel (thanks for the free hosting) and is designed to let you find code snippets in public github repositories FAST.
Usage
Aside from just finding things you're looking for you might want to get some insights into the types of things...
- Checking the usage of a dependency — copy and past the dependency from your project ans see how/where other users are using the same thing
- Finding security holes — as an ethical hacker you might want to find all the instances where public repositories are over sharing api keys and give them a nudge
The UI allows you to filter by
- Repository
- Path
- Language
and the search itslef has regular expressions, an option to match case and to match whole words.