How to send historical back in stock subscriptions from old system to klaviyo


I'm working on setting up the back-in-stock subscription feature on Klaviyo. I'm planning to transfer all current subscriptions from the existing system to Klaviyo. Is there a way to do this, such as uploading an XML or CSV file directly to Klaviyo, or using a bulk API accepts for an example 1000 subscriptions per request?


Best answer by dartacus 22 May 2024, 12:39

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Userlevel 2
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Yes, you can do this with a csv upload or API calls.

If it’s a one-off import, then just a CSV import to a list is by far the easiest way. Have a look at

If there’s going to be ongoing sign-ups using code on your site which you then import to Klaviyo, then go the API route. Have a look at as a possible starting point.

I’ve done both, the first is easy, the second just requires a bit of integration + edit access to your underlying site so you can invoke the API call when someone subs in. I have to update my integration to bring this into line with the newer API so if you go this route make sure you’re referring to the latest dox.




Hi @dartacus 

I followed the CSV import method, but it created a new metric called “Subscribed to back in stock” which is not what I want.


I need to sync all historical subscriptions to the system metric highlighted in green below.


Please let me know if you have any idea on how to do this!

Thanks a lot!

Userlevel 2
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That’s very strange.

Off the top of my head, all I can think of is to use API calls to read in the emails from the list you just added and then perhaps there would be an API way to trigger the subscribed to back in stock event for each of them.