A CodeExpress developer is responsible for designing, coding, and modifying software applications according to client specifications. They focus on improving the overall user experience by ensuring the software is user-friendly, visually appealing, and easy to navigate. They use languages like HTML, CSS, JavaScript, and others to develop the front-end and back-end of applications. They also test, debug, and maintain the software to ensure its optimal performance. Additionally, they collaborate with other team members, such as UI/UX designers and project managers, to understand user requirements and translate them into functional software.