Set up Klaviyo API key

Visit your Klaviyo account settings API Keys and create a Private API Key for Back in Stock as shown in the image below.

API Key Scopes

Please follow the following steps as numerated in the image below:

1. Name your API Key.
2. Select "Custom Key" from the Select Access Level section.
3. Select "Full Access" from the List row.
4. Select "Full Access" from the Profiles row.
5. Select "Full Access" from the Segments row.
6. Select "Full Access" from the Subscriptions row.
7. Save your changes and copy the generated API Key from the next screen

Setting your List for single opt-in

To set your list for single opt-in, visit your Klaviyo account settings Lists and select the list you want to use for single opt-in. Click on the list and select the "Settings" tab, then in "Consent". Scroll down to the "Opt-in process" section and select "Single Opt-in" as shown in the image below.

Important: Klaviyo will just discard the subscriber if the list is not set for single opt-in.