AbTest.io - A free url shortener with A/B testing features
Whatsmyserp - Powerful Rank & Serp Tracking. Completely Free.
GoodUI Evidence - People's A/B test results that show which UI ideas work best
SEOmator - SEO website analysis & audit tool
PreFlight - Preflight is an Automated Web Testing tool. Allows everyone to automate Web UI tests.
Panguin Tool by Barracuda Digital - See your website's Google organic visit data overlaid with Google's major algorithm updates and changes to easily identify the impact on your website. Technology by Barracuda Digital.