When comparing Katalon Studio vs NW.js (w/xvfb), the Slant community recommends NW.js (w/xvfb) for most people. In the question“What are the best headless browsers for testing?” NW.js (w/xvfb) is ranked 3rd while Katalon Studio is ranked 7th. The most important reason people chose NW.js (w/xvfb) is:
The integration of Node with the DOM in NW.js opens up a number of new options in how your headless testing workflow can be facilitated. The distinct separation of JavaScript contexts, the introduction of a separate node context, and the ability to cross communicate, offers a lot of power and flexibility.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Valuable Features
Pro CI tools
CI tools available for e.g. Jenkins and Teamcity.
Pro SOAP and REST
Supports both SOAP and REST testing.
Pro Node integration
The integration of Node with the DOM in NW.js opens up a number of new options in how your headless testing workflow can be facilitated.
The distinct separation of JavaScript contexts, the introduction of a separate node context, and the ability to cross communicate, offers a lot of power and flexibility.
Pro NaCl support/integration
Access to the Native Client offers up more options in implementing your testing workflow.
Cons
Con Does not support nested shadow root DOM structure
Con Not for desktop applications
Currently Katalon Studio supports Web, Mobile, and API automation testing.
Con Heavy file to download
Con No free version anymore
Despite promises made of "being free forever".
Con Slow sometimes
Con xvfb Requirement (for now)
Headless is on the NW.js roadmap, but for now xvfb is necessary to get going. The community has done the work and you can find the details here.