Constant Contact Integration

Last updated at:


Klaviyo's Constant Contact integration is designed to help you move from Constant Contact to Klaviyo. We don't recommend using both platforms at once other than during the interim period as you make the switch. The integration makes it easy to pull your data into Klaviyo, which is an integral step in migrating from Constant Contact to Klaviyo.

From Constant Contact, Klaviyo pulls in the following data:

  • When someone received, opened, or clicked an email
  • A list of recipients who have unsubscribed or bounced
  • Existing lists in Constant Contact (you can choose to create Klaviyo lists from your Constant Contact lists)

Data syncs from Constant Contact to Klaviyo once every hour.

The Constant Contact sync pulls new contacts from Constant Contact into Klaviyo so you don’t have to import them manually. Once your integration is set up, if a contact is added to a Constant Contact list, that contact will be synced into Klaviyo. However, if a contact is deleted from Constant Contact, they will not be deleted in Klaviyo.

Create an API Key for Constant Contact

You’ll need a Constant Contact API key to integrate your Constant Contact account with your Klaviyo account. Since Constant Contact outsources part of their API infrastructure to Mashery, you’ll need to generate your Constant Contact API key in Mashery.

Create a Mashery Account

Start by creating a Mashery account or logging in to your existing account if you already have one.

If you're creating a new account, use your own name and email address.

You will receive an email from Mashery. Open this email and click the link to confirm your new account.

Register an Application and Obtain an API Token

Next, you'll need to obtain an API token which you'll use to pass your data from Constant Contact to your Klaviyo account. You'll do this by registering a new application and requesting an API key and secret.

Now register a new app with Constant Contact.

Name your application. For example, you can name your application ConstantContact Integration. We recommend that you do not reference Klaviyo in your application name.

In the box titled Select which Web APIs this application will use, ensure that Issue a new key for Constant Contact API and Standard API Access are both selected.

Agree to the terms of service and click Register Application.

You will need your Constant Contact Key and Secret to integrate with your Klaviyo account. Make note of both, as you will need these values. These can be retrieved later by navigating back to My Keys on your new app settings and selecting the correct application.

Update your OAuth Redirect URI

Next, update your OAuth Redirect URI so your application can connect with your Klaviyo account.

Navigate back to your app settings and locate the application you just registered in the steps above. Click Edit.


Fill in these fields:

  • Name of your application: Klaviyo Integration
  • Website: enter your URL, including either http:// or https://
  • Please describe what your application will do
  • Redirect URI for OAuth calls: In this field enter
    Redirect URI Changes take approximately 10 minutes to take effect. During that time, calls using this API key will receive a redirect URI error response.
  • Register Callback URL: usually your website address but may vary depending on your setup.


Click Save. Your application is now ready to connect with Klaviyo.

Enable the Integration in Klaviyo

Next, use the Key and Secret from the application you registered above to connect your Constant Contact account to your Klaviyo account.

Log in to Klaviyo and navigate to Integrations. Find Constant Contact on the All Integrations tab, and click Add Integration.

Expand the Advanced Options. We suggest you enable both the Collect open and click data for Constant Contact campaigns and Create Klaviyo lists from Constant Contact lists options.


Click Connect to Constant Contact.

You'll be redirected to Constant Contact. If you are not already signed in, you'll be prompted to enter your username and password.

Click Allow. You should see the name of the application you registered.

You’ll be redirected back to Klaviyo where you will see a confirmation message at the top of the page.

Klaviyo will begin to sync your contacts and the past 90 days of your event data. After the initial sync, Constant Contact syncs with Klaviyo every hour.

Data Synced to Klaviyo

Once you've connected Klaviyo with Constant Contact, data will start syncing within a minute or two. If you navigate to the Metrics tab in your Klaviyo account, you should see several metrics for Constant Contact data (received email, opened email, and clicked email) each with a Constant Contact icon next to it.

While you may see the Received Email (Constant Contact) metric in your account, as shown above, Klaviyo does not currently record any of these events.

Migrate from Constant Contact to Klaviyo

Once your integration is enabled, you can walk through the process of fully migrating from Constant Contact to Klaviyo.

Head over to our article on Migrating from your Previous Email Service Provider to Klaviyo for more information. 

Best Practices

We want you to hit the ground running in Klaviyo. To ensure that you maintain good deliverability, you should only send your first few email campaigns to an engaged segment of your list(s) from Constant Contact. Since you'll have open and click data from Constant Contact, you'll be able to use this data to segment your lists.

If you email your subscribers more than once a week, you should send your first week of email campaigns to an engaged segment. For more information, head to our Guide to Your First Send.

Was this article helpful?
19 out of 32 found this helpful