Mercur is an open-source, enterprise-grade platform for building and operating multi-vendor marketplaces. Developed by Rigby, a team with experience delivering production marketplaces, it provides a buyer storefront, vendor panel, admin console, and integrations in one system. Organizations can use Mercur to add a marketplace alongside an existing Shopify, Magento, or custom store, or build a standalone commerce and marketplace platform.

The platform supports vendor applications and verification, product offers from multiple sellers, order splitting, vendor payouts, financial ledgers, approvals, dispute handling, and audit trails. Its API-first, headless architecture uses JavaScript and TypeScript, with typed APIs, developer tools, events, and reusable blocks for customization. Mercur is designed to run on any cloud, on-premise, or air-gapped infrastructure, giving customers control over their source code and data. The public standalone engine is MIT-licensed; the Enterprise edition adds production-focused capabilities such as payments, compliance, trust and security features, integrations, and enterprise support. Mercur charges no GMV fees and offers demos, documentation, and case studies to help teams assess the platform.