Jupyter - Project Jupyter exists to develop open-source software, open-standards, and services for interactive computing across dozens of programming languages. Ready to get started? Try it in your browser Install the Notebook.
Observable - Interactive code examples/posts
Observable Notebooks - The portfolio and technical blog of Chris Henrick – provider of professional web development, data visualization, GIS, mapping, & cartography services.
nbviewer.org - Rackspace server host Jupyter Notebooks from your github repo
Calculist - The open-source, web-based thinking tool that facilitates effective thinking for solving problems.
iPython - iPython provides a rich toolkit to help you make the most out of using Python interactively.