API-led integration is a method of connecting applications through the use of APIs, enabling seamless data synchronization across various scenarios. This approach can be employed for both internal integrations within a company and customer-facing integrations between a product and clients' applications. The benefits of API-led integration include improved employee experience by reducing manual data entry, prevention of human errors, increased close rates by offering more integrations, enhanced customer retention through better user experience, and the facilitation of market expansion by integrating with applications used by target markets. Merge offers a solution for building API-led product integrations at scale with a unified API, providing features such as common models, field mapping, integration observability, and maintenance support to ensure reliable integrations.