Our v3 API is now available! Learn more by visiting the v3 developer portal. Creating new v2 API keys is no longer supported.

Why Build with Us

The free, public Constant Contact API delivers an easy path to integrate with one of the top 3 brands most trusted by small business.  Integrating with Constant Contact lets you add value to your applications by enabling new product features and automating the synching of contacts and marketing results.

Your App + Constant Contact = More Successful Customers

Help your customers work smarter and faster by integrating with best-of-breed online marketing tools. We understand small businesses and nonprofits and how to help them succeed with online marketing including email marketing, event marketing, online surveys, social campaigns, local deals, and digital storefronts.

Our app partner program provides integration-specific on-boarding and educational resources to help your customers succeed. Tap into revenue share as high as 40% a month, co-marketing opportunities, and exposure to new customers along with our passion for the success of your business.

Integrating Is a Snap

The APIs are designed to be easy to use. We've built them around industry standards like REST, JSON, and OAuth 2.0, and included acceleration tools like development libraries including iOS, C#, and others, that include sample code for key tasks, an OAuth 2.0 token generator Go from start to test by making live API calls in minutes without having to write a single line code using our I/O docs. The API comes with in-depth documentation and responsive support on our Developer Portal.