What is an API?
An API, or application programming interface, is a set of rules that lets one piece of software talk to another. It defines what you can request, how to ask, and what you get back. Marketers use APIs to move data between platforms.
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How an API works
One system sends a request to a specific address, and the other system sends back a response. A request might ask for last week's ad spend or tell a tool to add a contact to a list.
Most web APIs return data in a structured format such as JSON. Access is usually controlled with keys or tokens so only approved tools can use it.
How marketers use APIs
APIs pull ad platform numbers into a data warehouse, send leads from a form into a CRM, and push conversions back to ad platforms. Many integrations you set up with a few clicks are APIs working behind the scenes.
Custom work becomes necessary when a built-in connector doesn't exist or doesn't carry the fields you need.
Limits to plan for
APIs often cap how many requests you can make in a period, and providers change them over time. Build in error handling and monitoring so a changed or failed connection doesn't go unnoticed.
Common questions
What does API stand for?
API stands for application programming interface. It's the agreed way for software programs to exchange information or trigger actions.
Do I need to code to use an API?
Not always. Many tools connect through APIs without code, using built-in integrations or automation platforms. Custom connections usually need a developer.
What is an API key?
An API key is a secret code that identifies who is making a request. Treat it like a password and don't share it or put it in public code.
What's the difference between an API and a webhook?
With an API, your system asks another system for data when it wants it. With a webhook, the other system sends data to you when something happens.
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