An iBatis developer primarily works on the iBatis framework, a persistence framework that automates the mapping between SQL databases and objects in Java, .NET, and Ruby on Rails. They design and implement data persistence layers, handle SQL database integration, and map objects to stored procedures or SQL statements. They use iBatis to simplify complex database structures into easy-to-use data objects, reducing the need for custom, manual data handling in applications. They are also responsible for troubleshooting, maintaining, and improving the performance of existing systems. They work closely with other developers, ensuring the seamless flow of data in the software.