Optimizely
VWO
AB Tasty
Google Analytics
Google Marketing Platform
PractiTest
Azure DevOps
Micro Focus ALM
Alchemy
Lokalise
OneSky
Crowdin
POEditor
Transifex
Weblate
WebTranslateIt
Optimizely
AlchemyOptimizely is a lower cost entry tool for anyone looking to do website testing. While their pricing structure has changed over the years it still is a pretty cost effective solution. It is easy to get tests up and running within 5 minutes once you have code placed on your site.
I love the drag and drop features of Optimizely. It makes it very easy to make simple changes to do landing page testing for my paid search campaigns. It also frees up dev time for our web team. Also, The findings from Optimizely tests are so valuable for an end customer experience.
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Lokalise - Localization tool for software developers. Web-based collaborative multi-platform editor, API/CLI, numerous plugins, iOS and Android SDK.
AB Tasty - AB Tasty is an all-inclusive platform for conversion rate optimization, personalization, customer activation, and testing.
OneSky - Full Stack Localization Solution
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.
Crowdin - Localize your product in a seamless way with Crowdin's translation management software