Updating API from V2 to V3

0 Votes
I have an existing API built out in V2. I know that Constant Contact is phasing this out for V3. I'd like to get my API updated to V3, but unfortunately can't seem to make heads or tails of the API documentation (I'm not a developer - original API was set up years ago before I joined current company). I'm wondering how to find/if someone can volunteer here a developer who is very familiar with the constant contact APIs and can assist with making this update. I've been authorized by my boss to pay market rate for this update.
0 Votes

Hello MaianneP,


Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.


Once you find a developer to assist with your project, the below info may be of use when updating from V2 to V3:


Our current V3 API uses OAuth2.0, which is the current industry-standard for authorization. It’s more secure and does a much better job of keeping your Constant Contact account data safe. When you give their integration permission to access your account, it will show you exactly which permissions the integration is requesting to be granted (rather than just granting all permissions). V3 also uses tokens that are continuously refreshed to keep the connection encrypted and secure, rather than just accessing the account via your username and password.


There are several significant differences between our V2 and V3 APIs, including the use of different endpoints, OAuth 2.0 rather than basic authentication, JSON payloads instead of XML, and a different format for resource identifiers.


A quick start guide for the V3 API can be found here:



While the rest of our documentation is linked from the quick start guide, the following pages in particular may be useful:





Additionally, you can utilize our API Reference tester to test out the functionality of our available endpoints to see how they will work once programmed within your application: 



While Constant Contact doesn’t offer any services as far as assistance with building custom integrations, and our expertise is with our API itself as opposed to its implementation within any particular programming language, we are happy to answer any questions pertaining to Constant Contact’s API endpoints, functionality, and documentation.


Please have a look and let us know if you or your developer have any other questions!

You can also reach our team directly at webservices@constantcontact.com


Courtney E.
Tier II API Support Engineer

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