Earlier research on online communication has observed how its distinctive characteristics (such as limited cues and potential asynchronicity) facilitate online communication notably 'hyperpersonal communication'. Yet these distinctive characteristics do not explain the development of trust in online communication. This article uses qualitative interviews with 17 internet users to explore the foundations of trust in online friendships, drawing on Piotr Sztompka's theoretical framework. It concludes that there are four main sources of online trust. First, reputation, whether grounded in a pseudonym or offline identity. Second, performance, due to the scope for enhanced performance in online communication. More than this, performance plays an especially important role in the building of online friendships, following Giddens' model of the pure relationship (1991). Third, pre-commitment, through self-disclosure, which in turn encourages a 'leap of faith' and reciprocal self-disclosure. Finally, situational factors, especially the premium placed upon intimacy and the pure relationship in contemporary societies.