A Liferay developer is responsible for designing, developing, and implementing applications using the Liferay Portal. They create and manage content management systems, collaboration software, and social networking sites. They use Java and technologies, Liferay APIs, Liferay Service Builder, and Liferay Hooks to customize the portal's functionality and user interface. Additionally, they integrate Liferay with other systems, troubleshoot issues, and optimize performance. They participate in the entire software development life cycle, including requirement analysis, design, coding, testing, and maintenance. They also provide technical support, documentation, and end-user training.