TheoremJS - A Math framework for computation in JavaScript
Artboard Studio - Online graphic design app mainly focused on product mockups.
The Data Visualisation Catalogue - Reference tool for data visualisation
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.
Flourish - Powerful, beautiful, easy data visualisation
ProtoSketch - Powerful yet simple vector graphics editor and prototyping