The following list of visual tools was compiled at KairosCamp I (August 2017). Kairos does not endorse these projects specifically, but wanted to provide a succinct list of resources for potential authors (we will be adding to our list periodically). Potential webtext authors should contact the editors before commiting to any interactive tools to discuss any issues or challenges these systems might pose (particularly in terms of hosting, publishing, and archiving webtexts with embedded third-party products).
Adobe Color CC
Data Visualization 101: How to Design Charts and Graphs
The Big Four: Contrast, Repetition, Alignment, Proximity
Clean Up Your Mess: A Guide to Visual Design for Everyone
Traci Garnder's list of Storyboard and Mockup Tools