Flinto - The prototyping tool designers have been waiting for.
Vidrio - Holographic screencasting app for Mac. Free for COVID-19
Base UI Sketch Framework - Huge set of everything you need to design and prototype
Scrimba - Interactive coding screencasts created in an instant
Glyphy - Copy & paste fancy fonts + cool symbols ☞✺✐™
GoRails - Ruby on Rails screencasts for Web Developers