As of version 9.0, IntelliJ IDEA is provided in two editions:
- Community Edition: open source and available free of charge. The Community Edition is covered by the Apache 2.0 license, and is built together with the open community around jetbrains.org.
- Ultimate Edition: professional and fully-featured commercial IDE provided by JetBrains. The Ultimate Edition is built on top of the Community Edition with many extra features for web and enterprise development. You can download IntelliJ IDEA Ultimate from http://www.jetbrains.com/idea. You can evaluate it for free for 30 days, purchase a license, or get a free license if you're a contributor to an established open-source project.
IntelliJ IDEA Community Edition is the perfect choice for those working on pure Java/Groovy applications or doing Swing development. It has all the crown jewels of IntelliJ IDEA, including various refactorings and code inspections, coding assistance, debugging, TestNG and JUnit testing; CVS, Subversion and Git support, as well as Ant and Maven build integration.
The complete breakdown of features included in IntelliJ IDEA Community Edition and IntelliJ IDEA Ultimate can be found in this comparison matrix.