Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
Artboard Studio - Online graphic design app mainly focused on product mockups.
Xamarin.Android - Integrated environment for building not only native Android but iOS and Windows apps too.
Image to Sketch - Convert images to pencil sketches with AI technology
Kodular - Much more than a modern app creator without coding
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.