Source Code Search Engines Overview

Wednesday, February 7th, 2007
by George Appiah

I’m not a programmer. Far from it. But I hang around with so many programmer friends (mostly online) that sometimes people (including myself) mistake me for one.

And I’m often amazed when I hear folks talk about the amount code out there already in the open source community for practically any project one can think of. But the problem, they’d usually add, is finding what’s already out there for your specific project.

That’s where code search engines come in. These are a new generation of search engines that allow you to search for source code from various projects and in various programming languages. Here’s a short overview of 4 of the more popular ones.

Google Code Search: As can be seen from the logo, this is still a Google Labs project, not quite ready for prime time. Google extends it’s simple and intuitive search interface to Code Search as well. On the “Advanced Code Search” page, you can opt to limit search results to a particular programming language or a particular license.

Google aside, there are a few startups who are also working to make code readily avaible to programmers. One of such startups is Krugle, which is built on Lucene, the open source search software. Krugle provides both code and project search, as well as links to related technical papers.

Koders is another startup in the code search arena. Koders has a simple search interface not too different from Google. They also have a nifty Firefox search plugin for all supported languages and for individual languages.

All The Code is another code search engine that was launched recently. Presently, All The Code only returns results for the Java language, so unless you’re a java juggernaut, this one will not be useful to you. Expect more languages to be added soon!

NO matter what search engine you use, I think an important issue you should not overlook is the type of license under which the code is released, if you’re going to re-use specific code in your projects (why re-invent the wheel?). While, I believe, all code returned in query results are free to use, some of the licenses might require that you also give away or make open whatever you do with that piece of code.

Sure, copyright laws are dead in Ghana … but you never know when someone will knock at your door to buy or invest in your project, product, or company (that’s what I’m here for ). If this were to happen, whether or not you have absolute right to the code behind your software will surely play a role in the valuation.

Have you used any of these code search engines before? Do you know of any other? Please share in the comments below.