Civic technology needs to be better understood in terms of the factors that promote representative public participation and impact. This paper reports on a mixed-methods study of a civic tech platform that enabled the public to provide feedback on public transport to the service providers. The overall aim of this research was to investigate the public’s use of a leading civic tech platform, FixMyTransport. The key findings were that: an effective and easy-to-use civic technology platform enables broad participation; data and process complexity need to be removed; factual information can be captured in situ with impacts, consequences and opinions added later; emotions (if important) need to be explicitly elicited; feedback to, and a ‘conversation’ with, the users is important for engagement, as is a feeling of being part of a community. These findings can contribute to the future design of civic technology platforms.Practitioner Summary: There is a lack of understanding of how ‘civic tech’ platforms are used and how they may be designed for maximum effectiveness. Multiple data collection methods were used to investigate a well-developed example of civic tech. Effective civic tech can enable broad democratic participation to improve public services.