Free Open Source Code Search Engines
There are couple of sites which indexes the open source code and provides support to search code. Recently Google announced that they removed code search support from Google code. This article provides pointer for code search engine sites.
Github is a most widely used open source repository. It helps to search code on their public repository.
Ohloh Code, the world’s largest, most comprehensive free code search engine. Koders has now merged with Ohloh to become your one-stop resource for both code and analysis.
Antepedia is the largest knowledge base of open source components with over 2 million current projects. Antepedia continuously aggregates data from various directories that include Google Code, Apache, GitHub, Maven, and many more. http://www.antepedia.com/
searchcode is a free source code and documentation search engine. API documentation, code snippets and open source (free sofware) repositories are indexed and searchable.
Krugle provides support search open source code from all programming languages. It has advanced search capabilities to search on function name, class name, project name etc.
GrepCode can be used to find Java projects, Java classes, interfaces, enums, annotations (Java Types), Java methods. In addition, GrepCode allows users to do stacktrace searches and find usages of classes and methods.
Codase is the source code search company with advanced source code understanding and xml index/search technologies.
It hosts huge amount of open source codes providing a much better coverage. With Codase, one can search functions, classes, strings, constants, macros, comments and other programming language constructs.
Debian Code Search (DCS) is a search engine for source code — it searches all the open source projects which are included in the Debian archive (the "main" distribution only, not non-free or contrib). Currently, that includes about 18000 packages with 140 GiB of source code.