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
Adobe XD - Adobe XD is an all-in-one UX/UI solution for designing websites, mobile apps and more.
Papermind - Papermind Slack App is a collaborative article-editing and document management platform for Slack
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.