This site hosts the "traditional" implementation of Python (nicknamed CPython). A number of alternative implementations are available as well, namely

• PyPy (a fast implementation of Python with a JIT compiler)
• IronPython (Python running on .NET)
• MicroPython (Python running on microcontrollers and in the Web browser)
• Stackless Python (a branch of CPython supporting microthreads)
• Jython (Python running on the Java Virtual Machine)

Other parties have re-packaged CPython. These re-packagings often include more libraries or are specialized for a particular application:

• Anaconda Python (a full Python distribution for data management, analysis and visualization of large data sets)
• ActiveState ActivePython (commercial and community versions, including scientific computing modules)
• Nuitka (a compiler that packages user code with CPython into a static binary for improved performance and IP protection)
• pyodide (a Python distribution for the browser and Node.js based on WebAssembly)
• winpython (WinPython is a portable scientific Python distribution for Windows)
• pythonxy (Scientific-oriented Python Distribution based on Qt and Spyder)
• Conceptive Python SDK (targets business, desktop and database applications)
• PyIMSL Studio (a commercial distribution for numerical analysis – free for non-commercial use)
• eGenix PyRun (a portable Python runtime, complete with stdlib, frozen into a single 3.5MB - 13MB executable file)

If you want to host and run Python in the cloud, these implementations may be right for you:

• PythonAnywhere (freemium hosted Python installation which lets you run Python in the browser, e.g. for tutorials, showcases, etc.)