Background: Online forums that enable peer-to-peer interaction are widespread and readily available. Aim: This study aimed to identify the reach, benefits, and potential harmful effects for visitors to an online forum embedded in a suicide prevention platform in The Netherlands. Method: The study collected web-based questionnaires from online forum users and moderated posts. Descriptive quantitative and qualitative analyses were performed. Results: The online forum had 330 members in 2017, of whom 130 were active users (posting at least one message). Respondents (n = 106) experienced from a high severity of suicidal ideation (78%). A minority (12%) visited the forum to find suicide methods and 3% to find a suicide partner. Among respondents who had visited the forum more than once (n = 49), 53% reported no changes in feelings directly after forum use, 35% felt better and 12% felt worse. Peer support and anonymity were the most mentioned benefits, whereas no personal contacts and few reactions to postings were perceived as limitations. Suicide threats and the search for methods were the main reasons for moderating posts. Limitations: Usage habits and user experiences were available from a relatively small group that visited the forum more than once. Conclusion: In its current form, the forum has a low reach with few benefits and a potential for harm for its users. With a questionable benefit-to-risk ratio, the added value of the online forum appears to be small.