Quip: Team Documents for Slack - Create, share and get notified about Quip docs in Slack
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Trainual + Slack Integration - Capture knowledge or access training right inside Slack
Invision - Prototyping and collaboration for design teams
Papermind - Papermind Slack App is a collaborative article-editing and document management platform for Slack
Sketch - Professional digital design for Mac.