Sourcegraph - Sourcegraph is a free, self-hosted code search and intelligence server that helps developers find, review, understand, and debug code. Use it with any Git code host for teams from 1 to 10,000+.
OpenGrok - OpenGrok is a fast and usable source code search and cross reference engine.
GrepCode - GrepCode.com is a code search engine built by developers for developers to search and browse open...
Insight.io - Best web-based IDE-like source code browsing and search tool
Open HUB - Open HUB is an open source directory that anyone can edit.
GitHub - Originally founded as a project to simplify sharing code, GitHub has grown into an application used by over a million people to store over two million code repositories, making GitHub the largest code host in the world.