---
title: "Connect Customer.io webhooks to Shopify Flow - Workflow Webhooks"
description: "Send Customer.io webhooks into Shopify Flow. Step-by-step setup with Customer.io's HMAC signature verified on every request, plus what the app checks and how to troubleshoot."
canonical: "https://docs.workflow-webhooks.app/how-to-connect-customerio"
---

# How to connect Customer.io to Shopify Flow

Customer.io reports back on the messages it sends - deliveries, opens, clicks, bounces, unsubscribes - through a reporting webhook. **Workflow Webhooks** turns that call into a **Shopify Flow trigger**, so your store can react to it: tag a customer, add an order note, send an internal email, update a metafield - anything Shopify Flow can do.

This guide sets up the whole path - Customer.io sends, Workflow Webhooks receives and verifies, Shopify Flow acts - with Customer.io's HMAC signature checked on every request, so nothing but Customer.io can start your workflow.

## What you can build

- Tag a Shopify customer whose email address hard-bounced, so campaigns stop targeting them.
- Write the last engagement date onto the customer record as a metafield.
- Email your team when a VIP customer unsubscribes.

Typical events to send: `email_delivered`, `email_opened`, `email_bounced`, `customer_unsubscribed`.

## Before you begin

- **Workflow Webhooks** installed on your Shopify store.
- **Shopify Flow** installed, which is free from the Shopify App Store.
- An account on Customer.io with permission to create webhooks.

## Step 1 - Create the webhook in Workflow Webhooks

1. Open **Workflow Webhooks -> Webhooks -> Create webhook** and give it a name you will recognise in Flow, such as `Customer.io events`.
2. Under **Authentication**, choose **HMAC**.
3. Under **Signature provider**, pick **Customer.io**. The app fills in the header, algorithm, signed payload and replay window for you - there is nothing else to configure.
4. Leave the secret empty for now and **Save**. Copy the webhook URL shown on the page.

See [Authentication](https://docs.workflow-webhooks.app/authentication.md) for the other authentication modes, and [Payload mapping and Flow variables](https://docs.workflow-webhooks.app/payload-mapping.md) for choosing which fields reach Flow.

## Step 2 - Add the endpoint in Customer.io

In Customer.io, open **Settings -> Workspace Settings -> Reporting Webhooks**, add a webhook with the URL you copied, and copy the signing key.

### How to find your Customer.io signing secret

The signing key of the reporting webhook.

[Customer.io's own documentation on webhook signatures](https://docs.customer.io/journeys/webhooks/) has the exact wording and screenshots for your account.

Paste that secret into the webhook's **Secret** field in Workflow Webhooks and save. From that moment every Customer.io delivery is verified before it reaches Flow.

## What this checks

| What | Value |
| --- | --- |
| **Signature header** | `X-CIO-Signature` |
| **Where the signature sits** | The whole header value |
| **What is signed** | `v0:{timestamp}:{body}` |
| **Signature** | HMAC-SHA256, hex encoded |
| **Timestamp** | The `X-CIO-Timestamp` header, as Unix seconds |
| **Replay protection** | None - this sender does not sign a timestamp, so every valid signature stays valid |
| **The secret** | Used as plain text. Paste it exactly as the sender shows it |

In the signed payload, `{body}` is the raw request body, byte for byte, and `{timestamp}` is the timestamp above.

A request that fails any of these is rejected with `401`, is recorded in [History and troubleshooting](https://docs.workflow-webhooks.app/history-and-troubleshooting.md), and never starts a workflow.

## Step 3 - Build the Shopify Flow workflow

1. In **Shopify Flow**, create a workflow and choose the **Workflow Webhooks** trigger.
2. Press **Record events**, then send a test event from Customer.io (or use **Send test** in Workflow Webhooks) so Flow learns the shape of your data.
3. Every webhook you own fires the same Flow trigger, so add a first condition on the **webhook id** to keep this workflow to Customer.io only. The id is shown on the webhook page.
4. Add your actions - tag a customer, add a note, send an internal email, update a metafield.

## Step 4 - Test it end to end

Trigger a real event in Customer.io. In **Workflow Webhooks -> History** you should see the invocation with status **Success**. If the signature was wrong you get a failed entry with the reason instead, and [Verifying signed webhooks](https://docs.workflow-webhooks.app/signature-verification.md) explains the signature tester that shows you exactly which step failed.

### The signature does not match

In this order: the **secret** (the most common cause - an extra space, or a key from the wrong environment), whether the sender is using a **different endpoint's** secret, and whether anything between Customer.io and the app **rewrites the body**. Signatures cover the raw bytes, so a proxy that re-formats JSON breaks them. The signature tester on the webhook page shows the exact text that was signed.

### I get 401 on every request

Check that the webhook's authentication is set to **HMAC** with the **Customer.io** provider selected, that the secret is filled in, and that Customer.io is posting to the URL exactly as the app shows it, including the code at the end.

### Nothing appears in History

The request never arrived. Re-check the URL in Customer.io, and look at Customer.io's own delivery log for the response it got. A `404` means a wrong or deleted webhook, a `429` means you are over your plan's invocation limit - see [Plans and usage](https://docs.workflow-webhooks.app/plans-and-usage.md).

### The workflow runs for the wrong events

Every webhook in your store fires the same Flow trigger. Add a condition on the **webhook id** as the first step of the workflow, or narrow the events you send from Customer.io.

## Related

- [Verifying signed webhooks](https://docs.workflow-webhooks.app/signature-verification.md) - every provider we verify, and how to describe one we do not.
- [Payload mapping and Flow variables](https://docs.workflow-webhooks.app/payload-mapping.md) - getting the right fields out of the payload and into Flow.
- [Duplicate delivery protection](https://docs.workflow-webhooks.app/duplicate-delivery.md) - what happens when Customer.io retries a delivery.
- [History and troubleshooting](https://docs.workflow-webhooks.app/history-and-troubleshooting.md) - the log of every request, with replay.