A Bitbucket developer works on Atlassian's Bitbucket, a Git-based code hosting and collaboration tool. They create, manage, and maintain repositories, and review code through pull requests to ensure quality. They also work on branch permissions and merge strategies for seamless team collaboration. They integrate Bitbucket with other Atlassian tools like Jira and Bamboo for better tracking and automation. They also work on implementing security measures, including user permissions and access control. Additionally, they may build add-ons using Bitbucket's API to customize and enhance functionality, and troubleshoot any issues users may face.