Pre-Launch Widget Templates - 100+ widgets for your pre-launch campaigns
AbTest.io - A free url shortener with A/B testing features
UI Temple - Curated collection of the best web page designs
GoodUI Evidence - People's A/B test results that show which UI ideas work best
Gradients for Sketch - Free UI gradients template with styles and fills
PreFlight - Preflight is an Automated Web Testing tool. Allows everyone to automate Web UI tests.