AbTest.io - A free url shortener with A/B testing features
Viewflux - Feedback, prototyping and collaboration for designers
GoodUI Evidence - People's A/B test results that show which UI ideas work best
Savahapp - The all-in-one design sharing, collaboration, workflow and app prototyping platform
PreFlight - Preflight is an Automated Web Testing tool. Allows everyone to automate Web UI tests.
Red Pen - Red Pen lets you upload your design, share a short URL, and get live, annotated feedback super-fast.