Software selection is a critical part of any software engineering project, as projects depend on a rich ecosystem of components and frameworks. Software engineers always find it challenging to select a trustworthy software product despite the availability of a large number of software selection tools. This study explores the trust factors in open-source and closed software selection from a practitioner’s perspective, to gain insight into perceptions of software trust. To this aim, we conducted semi-structured interviews with 24 software practitioners from different businesses, including 12 experts in open-source software selection and 12 experts in closed software selection. By summarizing we found: (1) software selection is affected by three categories of factors, being technical, organizational, and structural assurance factors; (2) the most important factors are technical factors and organizational factors; and (3) software selection process and trust factors differ depending on the project risk tolerance. In addition, we compared the trust factors derived from the interviews with those found in the literature. Our findings revealed that there is a difference between the two.