Hound is an extremely fast source code search engine. The core is based on this article (and code) from Russ Cox Regular Expression Matching with a Trigram Index. Hound itself is a static React frontend that talks to a Go backend. The backend keeps an up-to-date index for each repository and answers searches through a minimal API. Here it is in action:
Quick Start Guide
Using Go Tools
Install Go if you don't have it already. Hound requires version 1.4 or later You might also want to define a
GOPATHenvironment variable) (it defaults to $HOME/go if you don't explicitly have one set). If everything is installed properly,
go versionshould print out the installed version of go.
Use the Go tools to install Hound. The binaries
hound(cli) will be installed in your $GOPATH/bin directory. Your $GOPATH should be in your $PATH (