IntelliJ IDEA is a code-centric IDE focused on developer productivity. IntelliJ IDEA deeply understands your code and gives you a set of powerful tools without imposing any particular workflow or project structure. IntelliJ IDEA is your dream pair-programmer who knows its way around the codebase, makes great suggestions right when you need them, and is always ready to help you shape your code.

Features:

Intelligent code editor has all the smarts for understanding Java code; provides refactorings, code inspections and intentions, super-fast navigation — all that we have accumulated over the years.

Integrates with such essential tools as JUnit and TestNG, Ant and Maven, and popular version control systems: CVS, Subversion and git.

Provides IntelliJ IDEA's famous XML-Java interoperability and comprehensive Groovy programming language support.

The Swing UI designer complements the suite of tools for developing Java desktop applications — such as IntelliJ IDEA itself.

Platform:Cross Platform;                               License:Apache 2.0 license

Reference:https://www.jetbrains.com/idea/