Digital neighbourhood platforms (DNPs) – also called online neighbourhood networks or neighbourhood social networks – are still a relatively novel phenomenon, and little is known about their actual reach among citizens and about neighbourhood conditions which foster or impede their spread. We consider DNPs as a digital extension of conventional neighbourhood social capital and analyse their spread in comparison with the latter using a recent community survey in two large German cities with a probability sample of 2900 respondents in 139 neighbourhoods. The analysis is guided by the scholarly discussion on the potential of DNPs to reduce current inequalities in the distribution of social capital. The results showed that 18% of respondents in Cologne and 12% of respondents in Essen have used DNPs. Multilevel analyses revealed a strong negative association of neighbourhood ethnic diversity with user rates, in parallel to the same negative effect on conventional neighbourhood social capital. It is therefore reasonable to assume that pre-existing inequalities in social capital are replicated by DNPs. On the individual level, the use of DNPs was less dependent on strong social bonds than on conventional social capital. Comparing respondents who use DNPs to those who do not, the former group proves to be socially more connected, more trusting and more satisfied with their neighbourhoods.