Purpose - This study aims to investigate service modularization in a manufacturing firm, identifies service modularization processes and examines how these processes change the service module characteristics. Design/methodology/approach - The study is based on a longitudinal case study (2008-2017) of a manufacturing firm. The development of six service modules was analyzed using data from interviews with key informants, informal meetings and internal documentation. Findings - This study suggests five service modularization processes, and that service module characteristics, such as standardization and interconnectedness, change in different ways depending on the service modularization processes used. It further identifies two service modularization routes that each combine the service modularization processes in unique ways with replication as a key process to improve both standardization and customization. Practical implications - This study elaborates a framework for service modularization, which can serve as a guideline for developing service modules. It also highlights the differences between product and service modularization, suggesting that the role of service module characteristics such as standardization and customization is specific for services. Originality/value - This longitudinal case study (2008-2017) provides empirical evidence on service modularization and extends existing knowledge on service modularization processes and how they influence service module characteristics.