Offline supplementary service strategies for the online marketplace: Third-party service or marketplace service?

•We explore three kinds of offline service strategies for the online marketplace.•The marginal cost-revenue ratio plays a key role in the seller’s service strategy.•Marketplace authorised service generates the subsidising and revenue-enhancement effects.•Marketplace with a relatively low/high commission rate will offer its service.•Marketplace authorised service yields a win–win outcome for the seller and marketplace.