There are several online platforms and resources that can help you learn Python and practice it directly in your browser. Here are some of them:

1. Repl.it: An online code editor where you can write and execute Python code. It also supports collaboration and sharing, and has a repository of user-created programs that you can explore.

2. PythonAnywhere: A web-based environment that allows you to write, run, and host Python programs directly from your browser. You can even deploy web apps using Python frameworks like Flask and Django here.

3. Jupyter Notebook via Binder: Jupyter Notebook is a popular tool for data scientists that allows you to combine text, code, and output in a single document. With Binder, you can run Jupyter Notebooks directly in your browser without any setup.

4. Google Colab: Similar to Jupyter Notebook, Google Colab allows you to write and execute Python code in your browser. It’s integrated with Google Drive and provides access to free computational resources (including GPUs).

5. Codecademy: An interactive platform that teaches you how to code. They have an excellent Python course that covers the basics, data structures, modules, and more.

6. Codewars: A platform for competitive programming, where you solve coding challenges called “katas”. It supports many languages, including Python.

7. Hackerrank: Similar to Codewars, Hackerrank provides coding challenges and also includes a section specifically for Python.