線上平臺之銷售市場，為由平臺業者提供相關的基礎設施，並收取費用。在Epic Games, Inc. v. Apple Inc.案中，由Apple提供銷售平臺，使用者須藉由其應用程式內部支付系統購買產品，而Apple收取其中一定比例的費用。Epic Games公司認為Apple之行為涉及搭售與壟斷市場。本訴訟之主要管轄法院為美國，Epic Games公司雖試圖提起跨國訴訟，惟英國法院認為其無管轄權；歐盟意識到Apple於平臺上之壟斷行為，並啟動其他線上銷售廠商對Apple投訴之調查；澳洲競爭與消費者保護委員會則以法庭之友的身分出席本訴訟。為避免大型線上平臺獨占市場，國際亦有相對應之立法，美國提出《開放應用程式市場法》(草案)與《美國線上創新與選擇法》(草案)，歐盟則以《數位市場法》限制大型線上平臺之不當競爭行為。Epic Games公司亦與應用程式開發者組成「應用程式公平聯盟」，以維護公平使用平臺之權益。

Online platforms as the sales markets, which the platform operators provide the relevant infrastructures and charge fees. In the case of Epic Games, Inc. v. Apple Inc., Apple provides the sales platform, users must purchase products through its in-app payment system, of which Apple charges a certain percentage of the fee. Epic Games company claimed that the behavior of Apple involving tie-in and antitrust. The main competent court is in American, Epic Games company tried to file transnational litigation; however, the British believes that it has no jurisdiction; the European Union has noticed the antitrust behavior of Apple on the platform, and began to investigated other online sellers who complaint about Apple. Australian Competition and Consumer Commission participated in this case as an ‘amicus curiae’ (‘friend of the Court’). For avoiding the monopoly of the markets by large online platforms, there were corresponding legislation in the international, United States proposed the Open App Markets Act (draft) and the American Innovation and Choice Online Act (draft); moreover, the European Union adopted the Digital Markets Act to limit the unfair competition of large online platform. For maintaining the right of using platform fairly, Epic Games also associated the Coalition for App Fairness with App developers.