Sauce Labs - Test mobile or web apps instantly across 700+ browser/OS/device platform combinations - without infrastructure setup.
Selenium - Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that.
Katalon Studio - Built on the top of Selenium and Appium, Katalon Studio is a free and powerful automated testing tool for web testing, mobile testing, and API testing.
soapUI - SoapUI Pro is one of the most prominent API testing platforms around, allowing developers to quickly prototype the functions of their apps and get them to market with little hassle.
Ranorex Studio - Accelerate testing with Ranorex Studio, the all-in-one tool for test automation. For desktop, web, or mobile app testing, with easy codeless automation tools, a full IDE, robust object recognition, flexible reporting and built-in Selenium WebDriver.
Setapp - Your shortcut to prime apps on Mac, an App Store alternative