Hound is a self-hosted code search engine that indexes source code repositories and provides fast regular expression search results using a trigram-based index. It is designed to be deployed on your own infrastructure, enabling you to search across multiple public and private code repositories simultaneously.
The engine builds its search index by decomposing source code into three-character trigrams, which allows for fast substring matching with regular expressions. It supports searching across multiple repositories in parallel, returning results from the pre-built trigram index. Hound can index private repositories by authenticating via configured SSH keys or using local file paths, and it periodically polls configured repository URLs at a configurable interval to refresh the search index automatically.
The search index and repository metadata are stored directly on the local file system, eliminating the need for external database dependencies. The application is configured through a simple JSON file that specifies which repositories to index and how often to poll them for updates.