An Active Record developer designs, creates and manages database systems using the Active Record software pattern. This involves creating data models that represent and interact with information in the database. The developer also writes code to perform CRUD (Create, Read, Update, Delete) operations, handles data validations and associations between models. They ensure seamless data transactions, improve system performance, and maintain data integrity. Additionally, they often work with other software development tools and frameworks, like Ruby on Rails, to build comprehensive web applications. They also debug and fix any issues that arise in the database interaction process.