Which of the following is a web-based platform for sharing and collaborating on machine learning projects?

Kaggle is a web-based platform specifically designed for sharing and collaborating on machine learning projects. It provides a community where data scientists and machine learning practitioners can come together to compete in data challenges, share datasets, and engage in discussions. Kaggle also features a robust environment for running code, with access to various datasets and the ability to collaborate using kernels (code notebooks).

While Jupyter Notebooks is a popular tool for creating and sharing documents that contain live code, it is primarily a local or cloud-based environment rather than a dedicated platform for collaboration specifically around machine learning. GitHub, although an excellent repository for version-controlled code and collaboration, is not focused solely on machine learning projects. It can host various types of projects, including those unrelated to machine learning. DeepAI provides AI-related services and tools but does not primarily serve as a collaborative platform for machine learning projects.

Thus, Kaggle stands out as the platform explicitly tailored for collaboration and sharing in the realm of machine learning.