There are a variety of methods that can be used to monitor the productivity of hired developers. Such methods include setting clear objectives and expectations for each project, tracking progress and outcomes for each task, and providing regular feedback to developers on their performance. Additionally, tools such as project management software, time tracking software, and automated testing tools can be used to provide valuable data about the productivity of developers. Finally, regular check-ins with developers can also be used to gauge progress and discuss any issues or concerns that may arise.