Here's how you can download the Xcode app free for your Mac.
1. Go to the Xcode app preview page.
2. Click the View in Mac App Store button.
3. Click the Free button to download the app.
Here's a description and screenshot of Xcode for Mac:
"Xcode provides everything developers need to create great applications for Mac, iPhone, and iPad. Xcode 4 has been streamlined to help you write better apps. It has unified user interface design, coding, testing, and debugging all within a single window. The Xcode IDE analyzes the details of your project to identify mistakes in both syntax and logic, it can even help fix your code for you.
Xcode runs on OS X Mountain Lion and OS X Lion, and includes the Xcode IDE, Instruments, iOS Simulator, the latest Mac OS X and iOS SDKs, and hundreds of powerful features."