An API (Application Programming Interface) integration connects two or more software systems so they can exchange data and trigger actions automatically. When your CRM receives a new lead and your messaging platform automatically sends a welcome text, that's an API integration at work.
APIs are the standard way modern software communicates. Most business tools — EHRs like Athenahealth, CRMs like Salesforce and Follow Up Boss, accounting platforms like QuickBooks — expose APIs that allow external systems to read and write data.
API integrations differ from workflow automation platforms in that they're typically custom-built connections between specific systems, optimized for a particular data flow. They're more work to build but offer more control over exactly how data moves, how errors are handled, and how the integration behaves under load.
For businesses, API integrations are the foundation of both workflow automation and MCP servers. Understanding that your tools have APIs — and what those APIs can do — is the starting point for most automation projects.
Common examples: syncing patient intake form data to an EHR via its API, pulling real estate listing data from an MLS feed, or submitting insurance eligibility checks through a payer's verification API.