Courseroot - Biggest online course database on the web
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Alcamy - Free, open self-learning platform. Learn & teach anything.
MIT App Inventor - App Inventor is a cloud-based tool, which means you can create apps for phones or tablets right in your web browser.
Startup Stash - A curated directory of 400 resources & tools for startups
Bubble.io - Building tech is slow and expensive. Bubble is the most powerful no-code platform for creating digital products.