This paper examines the roles of external stakeholders in the business model development of new technology-based firms (NTBFs) from the perspective of the founders. Based on a longitudinal study of two Swedish NTBFs, semi-structured interviews, including timeline mapping, were conducted with the founders of each firm over a period of two years, drawing on retrospective data from the first year of founding. The findings reveal that stakeholder interaction is first initiated based on the position the stakeholder has in relation to the firm, whereas what tasks the stakeholder perform in relation to NTBF resource needs has greater consequences for the business model development. The roles of stakeholders further help shape founder perceptions of how to do business, although such influence may be limited over time. The results provide valuable insight into the influence of founders' perceptions and firms' business networks on the business configuration of NTBFs, revealing that business model development is both endogenous and exogenous. Specifically, the study provides some original insights around which roles stakeholders play in the early development of the business model and why these roles are necessary at certain points in time. © 2020 World Scientific Publishing Europe Ltd.