Download of CodeSearch 1.0 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software lies within Developer Tools, more precisely Webmaster Tools. We recommend checking the downloaded files with any free antivirus.
From the developer:
CodeSearch lets you search across multiple lines in source code and shows your search results by filesystem hierarchy. You can see the matching lines from the file and visually get a sense of how to narrow your search. You can define work spaces that correspond to any folder or Git repository you have checked out on your machine. You can quickly include or exclude results by file extension, narrow in on a specific term, and more.
You may want to check out more Mac applications, such as MacCVSClient X, AcidSearch Installer or AlbumEnabler, which might be related to CodeSearch.