---
title: "Send shoppers to Customer.io"
description: "Shopper ID with Customer.io: what's charged, what's supported, and how to connect it."
url: https://wholayer.com/help/destination-customerio
---

# Send shoppers to Customer.io

> Shopper ID with Customer.io: what's charged, what's supported, and how to connect it.

Category: Destinations

Included on the **Growth** plan and above.

## What you're charged
Before we charge, we check whether the shopper is already in your Customer.io. New shoppers cost 2 credits, once; shoppers already there cost 1 credit, are never duplicated, and get a **WhoLayer Returning Shopper** event instead.

## What Customer.io supports
- **Checks your list first:** yes.
- **Refunds bounces:** yes, bounces and spam complaints within 30 days.
- **Deliverability Guard:** a fixed cap of 50 new contacts a day (or your own setting, if lower), because we can't read your rates.
- **Holdout report:** no, so nobody is held out and every new shopper is sent.

## Connect it
1. In Customer.io, open **Account settings → API credentials** and create a **private key** (it starts with `sk_us_` or `sk_eu_`) for the workspace your store uses.
2. In WhoLayer, open **Destinations**, choose **Customer.io**, and paste the key. We pick the US or EU data center from the key.
3. Click **Send test**, then look for a person "avery.sample@example.com" with a **WhoLayer Shopper Identified** event.
4. Build a campaign triggered by that event (browse abandonment works best), and a second one on **WhoLayer Returning Shopper**.

## Good to know
- Customer.io's API has no account-wide 7-day bounce and complaint counts, so the Deliverability Guard uses a fixed daily cap.
- Customer.io has no order records we can read, so there's no holdout report.
- Refunds use the bounce and spam-report suppressions Customer.io's email provider keeps.
- Opted-out people are never sent, and opt-outs take effect immediately.
- We encrypt your key when you save it and only ever show its last characters.

## Related

- [How Shopper ID works](https://wholayer.com/help/shopper-id-how-it-works.md)
- [Shopper ID and Klaviyo: what you're charged for, refunds, the daily cap, and the holdout](https://wholayer.com/help/shopper-id-klaviyo-guarantees.md)
- [Klaviyo schema: WhoLayer profile properties and events](https://wholayer.com/help/klaviyo-schema.md)
- [Your responsibilities when you use WhoLayer](https://wholayer.com/help/customer-obligations.md)