The Fivetran REST API allows users to programmatically manage users, groups, and connectors for scaling data workflows and improving security posture. It offers efficient, consistent, and powerful ways to perform bulk actions, communicate with Fivetran from other applications, and automate human-led processes using codified logic. The API is used by organizations for creating and managing pipelines at scale, improving overall security posture, extending Fivetran through integrations with developer tools, and syncing data from customers to software products.