I'm an Open/Libre software fan as well, and JetBrains is really friendly to this world. Their community edition (which, by the way, is awesome, even without th

I'm an Open/Libre software fan as well, and JetBrains is really friendly to this world. Their community edition (which, by the way, is awesome, even without the features from the Ultimate edition) is released under the Apache 2.0 license, and many of the features they develop end up in the community edition. The source code is here: http://www.jetbrains.org/display/IJOS/Download http://www.jetbrains.org/display/IJOS/Download For example, Google's Android Studio is built on top of IntelliJ IDEA community edition.