Mercur is a versatile, open-source marketplace platform designed for retailers looking to integrate third-party vendors and for organizations aiming to create multi-vendor marketplaces in B2B, B2C, or hybrid formats. Leveraging the Medusa framework, it seamlessly merges marketplace functionalities and APIs with a robust operator admin console, comprehensive vendor management tools, and customizable storefront components. Teams are equipped to oversee seller accounts, manage product catalogs and offers, handle commissions, facilitate split orders, and administer inventory, shipping, returns, promotions, and seller payouts all in one place. Developers benefit from a TypeScript-based, modular architecture that allows for tailored workflows and storefront designs, enhancing the user experience. The core platform, licensed under the MIT license, can be deployed in various environments, including cloud, on-premises, or air-gapped systems. Additionally, an Enterprise edition, which comes with separate licensing, offers advanced modules focused on compliance, financial management, integrations, operational controls, and enhanced support for live production environments. This flexibility and scalability make Mercur an attractive choice for businesses seeking to expand their marketplace capabilities efficiently.