Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Artboard Studio - Online graphic design app mainly focused on product mockups.
BuildFire - BuildFire is the easiest way for small businesses to build a mobile app in a matter of minutes for iOS and Android.
Canva - Canva is a graphic-design platform with a drag-and-drop interface to create print or visual content while providing templates, images, and fonts. Canva makes graphic design more straightforward and accessible regardless of skill level.
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.
Image to Sketch - Convert images to pencil sketches with AI technology