Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Startup Toolkit - Interactive how-to guides to launch your startup
Bots UI Kit - Fully customizable Sketch UI Kit for Messenger Platform
App Launch Checklist - Planning tool for launching your app successfully
Landing UI Kit - Handcrafted UI components for landing pages
Where To Post Your Product - A curated collection of 280+ websites to share your startup