Swift is a general-purpose, multi-paradigm, compiled programming language developed by Apple Inc. for iOS, macOS, watchOS, tvOS, Linux, and z/OS. Swift is designed to work with Apple's Cocoa and Cocoa Touch frameworks and the large body of existing Objective-C code written for Apple products. It is built with the open source LLVM compiler framework.

Features:
- Compile and run your program
- View program output or detailed error
- Advanced source code editor with syntax highlighting, bracket completion and line numbers
- Open, save, import and share Swift files.
- Language reference
- Customize the editor

Limitations:
- Internet connection is required for compilation
- Maximum program running time is 20s
- Some file system, network and graphics functions may be limited
- This is a batch compiler; interactive programs are not supported. For example, if your program provides an input prompt, enter the input in the Input tab prior to compilation.