A Giraph developer works with Apache Giraph, a platform used for large-scale graph processing. They design and implement algorithms for analyzing large sets of interconnected data, such as social networks or web graphs. They ensure efficient data processing by optimizing the use of memory and computation resources. Their responsibilities also include data modeling, creating scalable solutions, troubleshooting, and resolving any system issues. They collaborate closely with data scientists, data engineers, and other stakeholders to understand requirements, develop solutions, and deliver insights from complex data sets. Knowledge of Java and Hadoop ecosystems is essential for a Giraph developer.