Google Code Search was a Google Lab product that launched in Beta in 2006. It was used for searching open-source code on the Web.
It allowed users to search for a specific language, package, file, or license and supported multiple formats such as tar.gz and tar and repositories like CVS, .zip, git, and Mercurial.
According to developers, the tool often came in handy and let them keep track of what codes were used by other developers, especially in APIs that weren’t all that well documented. It was also a quick way to find an API corresponding to the functionality they needed at the time.
Google announced the shutdown of the app on their blog on October 14, 2011. It was part of their “fall sweep”, and users could use the tool until January 15, 2012.
Good alternatives to Google Search Code are services like Krugle and searchcode.