New and improved Klaviyo APIs

Experience improved consistency and connectivity, clear naming and syntax, and expanded feature parity with our new APIs. Now available!

Learn how to authenticate, how data is stored, and how to make your first API calls.

Klaviyo's new and improved APIs are now available! Start building today!

Explore our previous API documentation. The v1/v2 legacy APIs are scheduled to be end-of-lifed on Jan 1, 2024.

Discover new guides

Learn about the differences between our v1/v2 APIs and our new APIs with this comprehensive comparison chart.

The new API surface now supports a thorough set of syntax for modeling relationships between resources. Learn more about using relationships.

JSON API’s general filtering syntax and its supported operations can be used across all new APIs.

Create applications for the Klaviyo platform using our developer toolkit.

Find quick solutions in a library of code samples crafted by Klaviyo experts.

Reach out to our robust developer community for additional troubleshooting help.

Discover tutorials and stories about building on top of Klaviyo.

Get a behind the scenes look at what goes into building Klaviyo and life as a Klaviyo engineer.