A Twitter Software Engineer designs, develops, and maintains software systems that power the platform. They work with large-scale distributed systems, optimizing performance, scalability, and user experience. Engineers collaborate with teams across product, design, and infrastructure to build new features and improve existing functionality. They use programming languages like Scala, Java, and Python while leveraging machine learning, data processing, and cloud technologies. The role requires problem-solving skills, coding expertise, and a deep understanding of Twitter's architecture and engineering principles.