PurposeExplore the effects of competition policy on an important competitive dimension of digital platforms, namely quality.Design/methodology/approachThe deterrence effect of competition policy should induce firms to compete on merits, with lower prices and higher quality for consumers. Deterrence, or the inducement not to infringe competition law, may depend on the harshness of penalties and/or the likelihood of conviction. We use competition policy indicators that are associated with these deterrence dimensions, allowing for non-linearities and interactions of the indicators. We use a unique data survey of digital gig platform users, that covers at least two dozen platforms and more than 50 countries. Quality is measured using multidimensional indicators of the level of satisfaction of platform users with different platform services. We control for platform user and country characteristics, including other regulatory indicators such as labor laws, to recover different effects.FindingsResults suggest that competition policy is relevant for differences in product quality across platforms and countries. Important non-linearities are uncovered, where substantive rules of competition policy interact with competition authority power. The effects depend on either level of the indicators, suggesting that deterrence effects depend upon a combination of both law in the books and competition policy practice.Practical implicationsThe estimates suggest a need to balance both dimension of deterrence, namely, strictness and effectiveness to expand the effects of competition policy on competition.Originality/valueThis is the first paper that explores the effect of competition policy on non-price or non-margin competition dimension. It is the first to study the effect on a sample of digital platforms. It contributes to the literature of deterrence effects of competition policy.