A Final Cut Pro X developer designs, develops, and maintains applications for this professional video editing software. They create customized plugins, effects, and transitions, enhancing the software's functionality based on user needs. They also fix bugs and address software issues, ensuring optimal performance. Additionally, they collaborate with other professionals like UX/UI designers to improve the software's user interface. They need to stay updated with the latest programming languages and technology trends to offer advanced features. Furthermore, they provide technical support to users, helping them understand and utilize the software more effectively.