Top Alternatives to Udacity

Khan Academy is a non-profit educational organization.

Coursera works with universities and other organizations to offer online courses, specializations, and degrees in a variety of subjects, such as engineering, humanities, medicine, biology, social sciences, mathematics, business, computer science, digital marketing, data science, and others.

Udemy.com is an online learning platform. It is aimed at professional adults who want to add new skills to their resumes, or explore their passions.

Wikibooks (Wikimedia Free Textbook Project and Wikimedia-Textbooks) is a wiki-based Wikimedia project hosted by the Wikimedia Foundation for the creation of free content textbooks and annotated texts that anyone can edit.

edX is a massive open online course (MOOC) provider. It hosts online university-level courses in a wide range of disciplines to a worldwide student body, including some courses at no charge.

SoloLearn provides coding tutorials mainly through its mobile app.

TED-Ed is an online QnA site.

Pluralsight is an online education platform that offers a variety of video training courses for software developers, IT administrators, and creative professionals through its website.

Wikiversity is a Wikimedia Foundation project devoted to learning resources, learning projects, and research for use in all levels, types, and styles of education.

OpenCourseWare Consortium provides opensource cources.

Eureka.in NSES provides educational 2D and 3D content.

iTunes U is an educational platform for iTunes.