When shopping online, consumers sometimes hesitate, for example, because they are uncertain about product quality, or they do not know whether the price is reasonable. In the offline shopping context, sellers can encourage purchases by complimenting consumers. This study aims to explore how digital platforms can adopt the compliment tactic to catalyze consumers’ purchase decisions. We hypothesize that online compliments, like offline compliments, can effectively reduce consumers’ uncertainties in online shopping and thus encourage purchases. We plan to run a lab experiment to test the hypothesis. This study enhances previous research on offline compliments and contributes to e-commerce research by providing causal evidence of how digital platforms can use compliments to influence consumer behavior.