Optimizely - A/B testing you'll actually use.
Smaller - Make your websites load faster
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
SE Ranking - All-in-One cloud-based SEO software for agencies, marketing teams and webmasters
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.
Screaming Frog - Screaming Frog is search engine marketing agency offering search engine optimisation and pay-per-click advertising services.