The non-commercial textbook https://www.bookofproofs.org/ was launched in 2014. It is open to both - students and educators - who want to participate as co-authors. All articles can be enriched by graphical and interactive elements, also for mobile devices.

The site uses the axiomatic method to systematically derive the foundations of different branches of mathematics, computer sciences, and physics. In the meanwhile, it offers thousands of definitions, theorems, proofs, and examples at undergraduate and university level.