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.
Calculist - The open-source, web-based thinking tool that facilitates effective thinking for solving problems.
Kajero - Interactive JavaScript notebooks - create good-looking, responsive, interactive documents.
iodide - Interactive, notebook programming environment for the web.
BeakerX - Open Source Polyglot Data Science Tool
Bl.ocks - Simple viewer for sharing code examples hosted on GitHub Gist.