Twister Testing is described as 'With Twister, developers can start testing immediately using reusable test configurations. The repeatable test cases make complexity manageable and ensure the results are predictable'. There are more than 10 alternatives to Twister Testing for a variety of platforms, including Windows, Linux, Mac, BSD and Online / Web-based. The best alternative is Selenium, which is both free and Open Source. Other great apps like Twister Testing are TestComplete (Paid), Robot framework (Free, Open Source), Testim (Paid) and Screenster (Freemium).
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.
Robot Framework is a generic test automation framework for acceptance testing and acceptance test-driven development (ATDD). It has easy-to-use tabular test data syntax and it utilizes the keyword-driven testing approach.
PhearJS renders dynamic webpages using PhantomJS: fetch a page, render it and return a pretty JSON object. PhearJS is offered as a hosted API as well as an open source solution that you can host yourself.
The Software Testing Automation Framework (STAF) is an open source, multi-platform, multi-language framework designed around the idea of reusable components, called services (such as process invocation, resource management, logging, and monitoring).
Citrus Integration Testing Automated integration tests for message protocols and data formats that you require! Test message interfaces with HTTP, JMS, TCP/IP, REST, SOAP, FTP, SSH, XML, JSON and more!
SAFS (Software Automation Framework Support) is a Multiplatform data-driven test automation execution services Features Data-driven test automation services supporting advanced NLS testing. Tool-independent implementation for long-term test automation success.