The purpose of this study was to determine the effect of posting messages, reputation and product reviews on online purchasing decisions at Shoppee. The type of research used in this study is a type of quantitative research with data collection methods used are field research, namely questionnaires. The sample in this study were consumers who had purchased products online at Shopee as many as 70 employees. Data collection techniques by distributing questionnaires to 70 respondents. The data analysis method uses multiple linear regression analysis, coefficient of determination, T test, and F test. The results of this study indicate that Posting Messages, Reputation and Product Reviews have an effect on Online Purchase Decisions at Shopee.