IntelliJ IDEA — The Most Intelligent Java IDE

IntelliJ IDEA is a code-centric IDE focused on developer productivity. The editor deeply understands your code and knows its way around the codebase, makes great suggestions right when you need them, and is always ready to help you shape your code.

Blazing Fast and Smart Code Completion

IntelliJ IDEA offers smart, type-aware code completion. It knows when you may want to cast to a type and is also aware of the run-time type checks that you made, after which you can perform cast and method invocation in a single action!
New in IntelliJ IDEA 10 — code completion auto-invoked instantly as you type.

Easier Multilanguage Editing

IntelliJ IDEA easily recognizes one language inside another — language injections, such as SQL inside a Java, HTML inside JavaScript, etc. For injections the editor provides appropriate coding assistance inline and a dedicated injection fragment editor.

These are just 2 things out of dozens that make IntelliJ IDEA different.

Community Edition — Free and Open IDE for Java

IntelliJ IDEA Community Edition is the open source version of IntelliJ IDEA, a premier IDE for Java, Groovy and other programming languages.

* Intelligent code editor understanding your code, with refactorings, code inspections, intention actions, easy navigation and full Java 7 support.
* JUnit and TestNG integration and a convenient test runner UI.
* Maven and Ant-based project setup and building.
* Comprehensive Groovy programming language support plus plugins for Scala and Clojure.
* Google Android development including latest SDK support.
* Unified UI and experience for most popular version control systems: Subversion, Git, Mercurial and CVS. Visual merge, diff and changelists.
* Powerfull XML editor with XML-Java interoperability.
* The Swing UI designer for developing Java desktop applications.

Ultimate — Exclusive Out-of-the-Box Feature Set

IntelliJ IDEA Ultimate is the full-featured commercial IDE — with a complete set of tools and integrations with the most important modern technologies and frameworks, such as Spring
and Hibernate — a must-have for effective Web and Java EE development.

* Enterprise technologies support including Java EE, Spring, GWT, Struts, Hibernate, Google App Engine, OSGi and others.
* Simplified web development with intelligent editors for HTML, JavaScript, CSS, integration for templating engines.
* Full array of supported languages, with refactoring capabilities: ActionScript, PHP, Groovy, Scala, Python/Jython, Ruby/JRuby, Clojure.

* Deployment and debugging with any of the following application servers: Tomcat, GlassFish, JBoss, Weblogic, WebSphere, Geronimo, Resin.
* Commercial version control systems support: Perforce, ClearCase, Team Foundation Server, Visual SourceSafe.
* Tools for working with large scale Java codebases: dependency analysis and validation, UML class diagrams.