Nightwatch.js, built on Node.js, is an open-source automated testing framework that simplifies end-to-end testing for web applications using Selenium JavaScript. It provides a comprehensive suite of features including an inbuilt test runner, cloud service integration for cross-browser testing, and support for continuous integration, making it a popular choice among developers. The framework allows for flexible configuration using JSON files, enabling parallel test execution and seamless integration with CI/CD tools like Jenkins. The tutorial emphasizes the ease of setup and configuration of Nightwatch.js, along with the challenges associated with local infrastructure for Selenium testing, advocating for cloud-based solutions like LambdaTest to enhance test coverage and scalability. By integrating with cloud-based Selenium grids, testers can access a wide range of browser and operating system combinations, simplifying the maintenance of automation frameworks and enhancing testing efficiency.