Improved API for Easy List Subscription & Profile Management

Klaviyo logo in a cloud

One of Klaviyo’s strengths is our flexible API that allows developers to integrate any app or service with Klaviyo. When it comes to data-driven marketing, having the right data in your marketing platform is a must-have. We strive to build API-first, so as we add more functionality to our platform, we’re also updating our APIs to ensure developers can seamlessly work with Klaviyo the way they want.

We’re happy to announce the release of the new Groups API and version 2 of our List API. This new release has cleaner response data which speeds up API calls to get you your data fast. It also gives more nuanced abilities to manage your subscriptions and list memberships, add and edit profile properties without changing a customer’s relationship with your business, and retrieve profiles.

Get all Profiles from a List or Segment

Klaviyo allows you to export profiles from your lists and segments, so we wanted to give you that same functionality via the API. The new /group endpoint gives you the ability to pull all profiles from any list or segment in your account. Make a single call to retrieve a quick sample of profiles or loop your calls and retrieve all contacts from a given list or segment. Now it’s easier than ever to work directly with the Klaviyo API to retrieve list contacts for analysis or to sync them with your other marketing platforms.

Faster and More Flexible Profile Management

In the spirit of making things powerful, we overhauled our existing List API. Not only is the V2 API cleaner, faster, and easier to use, it also includes a new endpoint to manage your subscribers. The new /subscribe endpoint allows you to formally subscribe, re-subscribe, and unsubscribe profiles from lists. Every call to this endpoint will also post a subscribe or unsubscribe event to the profile’s timeline, making it easier to account for API-based signs up in your flows and segments. None of these awesome benefits are possible with the V1 List API, so if you’re currently using the V1 /members endpoint to pass sign up form submissions to Klaviyo, you will need to switch to V2 /subscribe.

Subscriptions are great, but we understand that sometimes you just need to update a few profile properties. By creating a distinct /subscribe endpoint, the updated /members endpoint can now be exclusively used to add and remove profiles from Klaviyo lists without changing their subscription status. This is great for handling preference updates or sending new customer property data into klaviyo. This endpoint also gives you the ability to add or remove profiles from a list without subscribing or suppressing them, giving you the ability to create static groupings of customers without inadvertently compromising the customer’s relationship with your business.

NOTE: If you are currently using Klaviyo’s V1 List API, you will need to transition to the V2 prior to January 2019, when support for V1 will be dropped.

For detailed information on how to implement this new API, read our docs. As always, please let us know if you have any questions or feedback by sending an email to with the subject line “I have an idea”!

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