There is no official online GDB (GNU Debugger) specifically designed for Python. However, there are several other online Python debugging tools and platforms available that can help you with debugging Python code. Some of them include:

1. Python Tutor: Python Tutor is an online platform that allows you to visualize and debug Python code step-by-step. It provides a visual representation of how the variables change during execution.

Website: http://pythontutor.com/

2. Repl.it: Repl.it is an online IDE (Integrated Development Environment) that supports multiple programming languages, including Python. It provides a debugging interface and the ability to execute Python code in real-time.

Website: https://replit.com/

3. Codepad.co: Codepad is a collaborative online code editor and compiler that allows you to write, compile, and execute Python code. It doesn’t offer a full-fledged debugger, but you can add print statements to debug your code.

Website: https://codepad.co/

4. PyCharm Educational Edition: PyCharm is a popular Python IDE developed by JetBrains. The Educational Edition of PyCharm is free and includes basic debugging capabilities, which can be helpful for learning and debugging Python code.

Website: https://www.jetbrains.com/pycharm-edu/

Please note that the availability and features of online tools may have changed since my last update. For the most up-to-date information, I recommend searching for “online Python debugger” or “online Python IDE” to find the latest tools available as of 2023.