UE Marketplace is described as 'The Marketplace is the e-commerce platform through which content creators connect with developers using Unreal Engine 4 by providing a wealth of game-ready content and code' and is an website in the Development category. There are eight alternatives to UE Marketplace, not only websites but also apps for Mac and Windows. The best alternative is Sell My App. It's not free, so if you're looking for a free alternative, you could try Chupa Mobile or Noodlio. Other great sites and apps similar to UE Marketplace are Unity Asset Store (Freemium), Scirra Store (Freemium), YoYo Games Marketplace (Freemium) and Game Creator Store (Freemium).
Sellmyapp.com is one of the first marketplaces for buying and selling mobile source code. The marketplace strives to enrich and push the mobile developer community to innovate by offering a wide variety of options to make new income streams as a mobile developer.
YoYo Games Marketplace is the asset and tooling store for GameMaker: Studio, offering an accessible way for asset creators to get their products to game makers and an easy way for game makers to find tools, graphics, sounds and more.
Game Creator Store offers a massive collection of royalty free 2D game assets, 3D game assets, 3D models, 3D objects, textures, audio, sound effects and more for modelling software and game development software provided by hundreds of fantastic artists.