Internationalization is seen as a commercial opportunity and, in some circumstances, necessary for many firms' resilience in today's volatile and unpredictable global marketplace. Most exporting organizations must cope with various emergent e-commerce digital platforms, given the rising importance of digital and technological transformation of modern international trade and its related strategic challenges. The spread of third-party multi-sided platforms (TPMPs) and established actors such as Amazon, eBay, and Alibaba, has led research to overlook evaluations involving other types of multi-sided e-commerce platforms, such as content management systems (CMSs). Nevertheless, these other platforms are evolving by leaps and bounds and changing the rules of the game for e-commerce website development. This study draws on the transaction cost economics perspective and theory of boundary choices to shed light on the differences in manufacturing firms' internationalization performances from the reliance among CMSs and TPMPs. The study retrieves data from a survey of 263 manufacturing firms' managers and executives relying on structured equation modeling. The findings outline that adopting CMSs partially mediates the relationship between e-commerce strategic commitment and internationalization performances. In contrast, TPMPs negatively moderate the relationship between e-commerce commitment and CMS and between e-commerce commitment and internationalization despite directly partially enhancing internationalization performances. Finally, the study reveals an inverted U-shaped relationship between e-commerce commitment and TPMP reliance.