The ability to quickly design and deliver a product is especially important within Engineer-to-Order (ETO) industry, and a successful product delivery within ETO requires significant amount of data exchange and integration amongst systems and stakeholders of the order fulfilment process. This necessitates that the systems and digital infrastructure supporting this process have the required amount of interoperability to exchange and use data from each other. However, despite being of strategic importance, interoperability has received limited attention in ETO literature. Therefore, the purpose of this article is to analyse the current body of academic literature and explore how interoperability has been approached within low-volume ETO industry. A literature review of 41 articles was conducted to provide an overview of how interoperability has been approached in existing ETO research, what technologies are enabled by it, and the most prominent approaches of improving interoperability within ETO industry. The literature review indicated that five categories of advanced technologies within ETO industry are enabled by interoperability: cloud computing, digital twins, cyber physical systems, blockchain and large scale collaborative data ecosystems. Furthermore, the review identified six prominent approaches to increasing interoperability, including knowledge management frameworks, data standardization and variation management, enterprise and manufacturing platforms, middleware, asset administration shells and semantic decision support systems.