Top 5 open source IDE

1) NetBeans

Netbeans is a robust IDE for developers that allows developers to create web, desktop and mobile applications. While Java is the main language supported by NetBeans, it is also extensible and plugins can be installed easily to support C, C++, Ruby on Rails and PHP to name a few.

NetBeans also sports an impressive GUI builder that helps build good front-ends for your application without any hassle.

The only drawback is that the Java code automatically generated by NetBeans is quite messy and cannot be refactored easily. NetBeans also offers good static analysis to detect errors in your code as your typing them out.

Another cool feature is that you can access your databases and servers from within NetBeans itself, allowing coders to stop and start servers directly from the interface.

2) Eclipse Juno

One of the most popular software IDEs around, Eclipse has just released a new version called “Juno” in June 2012. Eclipse is a feature-packed development environment, and can be downloaded as a complete package, or just platforms for Java/C++ development.

Though it is a free software, Eclipse has enterprise-level features, including an integrated Unit testing suite and static code analysis tools, including smart autocomplete features that suggests class functions to accelerate the coding process.

There are also a plethora of plug-ins that can be downloaded and installed to Eclipse that allow great extensibility for devlepment. However, due to the vastness of features available in Eclipse, it can be a bit intimidating to novice programmers. The good thing is that there are plenty of Java tutorials on the net catered specifically for Eclipse, helping to shorten the learning curve.

3) Visual Studio Express

One of the most standard platforms in the industry, Visual Studio has made a name for itself as a stable and useful coding tool. Visual C# express is a powerful tool that can be used to develop applications that run on the .NET framework.

Visual C++ express allows developers to make native Win32 applications. Visual Studio has good features such as IntelliSense, which is Microsoft's version of autocompletion, that helps coders to complete function names and variable names without developers having to look them up constantly.

Visual C# can also be used with XNA Game Studio to develop games for Windows and Xbox 360. Visual Studio Express is available here.  

4) Code::Blocks

Code::Blocks is a free IDE that supports many compilers in C and C++, and can also be extended to support other languages.

One of the favorite features of this IDE is the customizable syntax highlighting and code folding, which makes code more readable to the programmer. It comes with a full breakpoint debugger.

Another useful feature is that you can import your projects seamlessly from other IDEs, such as Dev C++ and Visual C++.

5) Aptana Studio

Aptana is the best free IDE for building web applications. Aptana is specifically designed to support rapid web development, with features for code assisting in HTML,CSS, Javascript and PHP.

Another very useful feature in Aptana's code assist is that it includes information on browser support for various  javascript methods and HTML elements. Ruby on Rails is also supported through RadRails, a plugin that supports full development on the Rails platform.

The integrated debugger is great at detecting bugs in Ruby and Javascript code, making life way easier for developers who used to simulate code repeatedly in browsers to check if it worked.