Selenoid is described as 'free open-source replacement of Selenium Grid running browser tests in Docker containers. It is known to work in big clusters with 5000+ parallel browsers, scales with no downtime and is used all over the world'. There are six alternatives to Selenoid for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and SaaS. The best alternative is Selenium, which is both free and Open Source. Other great apps like Selenoid are Cypress.io (Free, Open Source), puppeteer (Free, Open Source), LambdaTest (Freemium) and Moon (Paid).
Selenium is a suite of tools specifically for testing web applications. Selenium IDE is a Firefox add-on that records clicks, typing, and other actions to make a test, which you can play back in the browser.
Moon is a Selenium-compatible browser automation solution created to work in Kubernetes or Openshift cluster. It works out of the box, can be installed to a running cluster in minutes and comes with a set of ready-to-use images for the majority of popular browser versions.