SCIM (System for Cross-Domain Identity Management) is a RESTful API that enables Service Providers and Identity Providers to exchange user provisioning and identity information. It allows IT teams to manage employee access to apps and services, making it easier for startups to close enterprise deals and drive adoption within those customers' workforces. SCIM helps developers win sales by simplifying the onboarding process for new users at scale, standardizing protocols across different platforms, and providing more secure real-time updates compared to alternatives like SAML. Implementing SCIM can be challenging, but using a dedicated provider like WorkOS can help streamline the process.