n8n + Klaviyo Seed List Automation

 

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This n8n workflow automatically updates a Klaviyo list every day. It randomly selects a slightly larger group of profiles from a source list and replaces the campaign list with the new selection, helping your audience grow naturally while keeping recipients fresh and varied.

Workflow Summary

How it Works

The workflow executes the following steps each time it runs:

Fetch all profiles from the source list. The workflow paginates through the source Klaviyo list, collecting all available profiles.

Deduplicate and shuffle. Duplicate profile IDs are removed, then the full list is randomly shuffled using the Fisher-Yates algorithm.

Determine the new target count. The current size of the main list is retrieved. A random growth rate between 4% and 7% is applied to calculate how many profiles to add during this run.

Clear the main list. If the main list already contains profiles, they are all removed using a DELETE request.

Populate with new profiles. The shuffled source profiles are sliced to the target count and added to the main list using a POST request.

Node Reference

Execution Flow

Credentials

This workflow uses two separate Klaviyo API credential entries in n8n. Both must be configured with valid Klaviyo private API keys before the workflow is activated.

To set up credentials in n8n: navigate to Credentials → New Credential → HTTP Header Auth, and set the header name to Authorization with value Bearer YOUR_KLAVIYO_PRIVATE_KEY.

All Configuration Parameters

Growth Rate Calculation

Each time the workflow runs, the Build Delete Payload node calculates a new target size for the main list.

growthRate = 1.04 + Math.random() * 0.03 // results in 4%–7% growth
newCount = Math.round(currentCount * growthRate)
cappedCount = Math.min(newCount, totalInSource) // never exceeds source list size 

The growthRate variable generates a random growth rate between 4% and 7%. The newCount variable calculates the new target size based on the current number of profiles in the main list. Finally, cappedCount ensures that the target size never exceeds the total number of profiles available in the source list.

If the main list is empty (currentCount = 0), the workflow uses a base count of 30 profiles to bootstrap the first run.

Shuffle Algorithm

The Get & Shuffle Source Profiles node uses the Fisher-Yates (Knuth) shuffle algorithm to randomly shuffle all profiles in the source list. This ensures that every profile in the source list has an equal chance of being selected each time the workflow runs.

Pagination

The Get Source List Profiles node uses Klaviyo's cursor-based pagination to retrieve all profiles from the source list.

A 1-second delay is added between requests to respect Klaviyo's API rate limits. Pagination automatically stops when the response no longer contains a next link.

Conditional Delete

The Has Profiles to Delete? node checks whether the main list contains any profiles before sending the DELETE request.

If the main list is already empty, the DELETE request is skipped. Both branches then continue to the Build Add Payload node, so the add step always runs regardless.

Setup Checklist

Before activating the workflow, configure both Klaviyo Auth and Klaviyo Update List credentials in n8n using valid private API keys.

Next, update klaviyo_list_id_main and klaviyo_list_id_source in the Set Workflow Global Variables node.

Verify that 2026-04-15 is still a valid Klaviyo API revision, or update it to the latest available version if needed.

Run the workflow manually once with a small source list to verify that all API calls complete successfully.

Once everything has been verified, activate the workflow to begin the daily schedule.

Notes and Limitations

This workflow currently supports only one source-main list pair. To manage multiple pairs, duplicate the workflow or extend the Set Workflow Global Variables node to loop through multiple pairs.

Klaviyo's API accepts up to 1,000 profiles per request. If the target count exceeds 1,000 profiles, the Add Random Profiles node may need to be updated to send requests in batches.

Only profile IDs are transferred. No profile attribute data, such as email addresses or names, is read or modified.

A 1-second delay is applied between pagination requests. If the source list contains more than 10,000 profiles, the workflow execution time will increase accordingly.

If the DELETE request succeeds but the POST request fails, the main list will remain empty until the next scheduled run or until the workflow is run manually again.

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Example of Use

Before you can use this automation, you need to complete a few setup steps.

Step 1: Configure the Workflow Variables

The first thing you need to do is set up the global variables used by the workflow.

1. Open the workflow in n8n.
2. Find the Set Workflow Global Variables node.
3. Double-click the node to open it.
4. Update the required values with your own information before running the workflow.

These variables are used throughout the entire automation, so make sure all the information is correct before moving to the next step.

Step 2: Once you open the node, you will see a window similar to the one below.

Now, update the following variables with your own List IDs:

1. klaviyo_list_id_main
   This is the ID of the completely new list you just created. This list will be used in the future for sending daily warm-up emails, gradually increasing and rotating them.
2. klaviyo_list_id_source
   This is the ID of the list you previously created with the client that contains all of the splits. It can contain 2,000, 5,000, or any other number of contacts.

Replace the example values shown in the highlighted fields with your own List IDs, as shown in the image below.

Step 3: Next, you need to set up the API connection for the four HTTP Request nodes in the workflow.

You can use the same Klaviyo API key that you created for the previous workflow (such as the Update and Rotate Seed List workflow), or you can create a new one. If you create a new API key, make sure it has List permissions enabled.

To configure the connection, either edit the existing credential or create a new one.

According to the Klaviyo documentation:

• In the Key field, enter Authorization.
• In the Value field, enter Klaviyo-API-Key (including the space after it), followed by your Klaviyo API key.

Authorization: <Klaviyo-API-Key> <your-private-api-key>

Once the API connection is configured for all four HTTP Request nodes, the workflow is ready to run. You can Execute the workflow to test.

Download - Klaviyo Update List For Campaign.json