Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Jasonette - Make an app by adding JSON to this app.
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.
AppyBuilder - An App Inventor 2 spin-off. Formerly called AILiveComplete.
Bubble.io - Building tech is slow and expensive. Bubble is the most powerful no-code platform for creating digital products.
AppMySite - An automated no-code app builder