StartupResources.io - Tightly curated lists of the best startup tools
SketchTool - Export pages & slices out of .sketch docs using CLI
Startup Stash - A curated directory of 400 resources & tools for startups
Select Similar Layers - Sketch plugin to select layers with the same attributes
Happy Startup Canvas - A simple framework for building stuff that matters
Base UI Sketch Framework - Huge set of everything you need to design and prototype