Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Kingfisher - Organize and explain just about 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.
Explained Visually - An experiment in making hard ideas intuitive.
Bubble.io - Building tech is slow and expensive. Bubble is the most powerful no-code platform for creating digital products.
Crowdcast - CrowdCast provides webinars & virtual conferences.