Optimizely - A/B testing you'll actually use.
Google Analytics - Improve your website to increase conversions, improve the user experience, and make more money using Google Analytics. Measure, understand and quantify engagement on your site with customized and in-depth reports.
StatCounter - StatCounter is a simple but powerful real-time web analytics service that helps you track, analyse and understand your visitors so you can make good decisions to become more successful online.
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Matomo - Matomo is an open-source web analytics platform
Optibase.io - A/B test or split test your Webflow site with Optibase. Test everything from copy to design or even entire pages and improve your conversions.