Express, a Node.js web application framework, is designed to provide a minimalistic yet flexible solution for mobile and web applications by offering server-based logic. The development of Express-based applications involves various phases such as requirement gathering, analysis, coding, and testing, with both manual and automated testing being crucial. Express testing can be enhanced using frameworks like Mocha, Chai, Jest, and SuperTest, which simplify testing processes with features like easily readable syntax and support for unit testing. Additionally, cloud-based platforms like LambdaTest offer cross-browser testing capabilities, supporting over 3000 browser versions, and enhancing collaboration through integrations with bug management tools. Express.js is part of the MEAN software stack, facilitating backend operations, and is favored for its asynchronous coding, code sharing, and efficient performance despite some limitations in API stability. The growing demand for software applications necessitates adopting automated testing for efficiency and comprehensive test coverage, making tools like LambdaTest valuable for ensuring cross-browser compatibility.