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Customer.io Webhooks

Customer.io lets you subscribe to reporting webhooks. This page details the events that we report back to your webhook URL.

Reporting webhooks

Set up webhooks to inform an external service about Customer.io events. Webhooks can notify you immediately when customer attributes change or when people open your messages.

Set up webhooks

Log in and go to Data & Integrations > Integrations.
Find and select Reporting Webhooks.
Click Add Reporting Webhook.
Enter the Webhook Endpoint—the URL where you want to receive events. The URL can be either HTTP or HTTPs, but we recommended HTTPS to protect customer information.
Select the events you want to receive.
(Optional) Select the Send Frequency and Body Content options.
- Send Frequency: This determines whether you receive events the first time they happen or every time they happen.
- Body Content: Enable this to include message body content in all of the "Sent" events we send to you.
Click Save and Enable Webhook.

Timeouts and Failures

Webhooks have 4 second timeout. If Customer.io does not receive a successful (2xx) response during those 4 seconds, Customer.io will retry the webhook over a 7-day period with an exponential backoff. We will not move past a failing webhook until we get a successful (2xx) response or until 7 days have expired. Subsequent webhooks will be backlogged and will get processed after the success or failure of the webhook that failed and triggered the backlog.

If you wish to temporarily block our servers, you can look up the current set of IP addresses we use via this API endpoint.

Securely Verifying Requests

For security purposes, every email webhook is delivered with an X-CIO-Signature header. This signature is generated by combining your webhook signing key with the body of webhook request using a standard HMAC-SHA256 hash. You can find the signing key on the Email Activity Webhook integration page in your account settings. (This is the same page where you enter your webhook endpoint.)

To validate a signed request, first you'll need to retrieve the X-CIO-Timestamp header sent with the webhook request, and the body of the request. Combine the version number, timestamp and body delimited by colons to form a string in the form v0:<timestamp>:<body> (the version number is always v0). Using HMAC-SHA256, hash the string using your webhook signing secret as the hash key. Compare this value to the value of the X-CIO-Signature header sent with the request to confirm that the request originated with Customer.io.

Reporting webhook format Webhook

Customer.io sends events to your webhook URL in the following format. Events are generally organized by object_type—representing the message or Customer.io action (i.e. email, sms, etc)—and the specific metric pertaining to the type (i.e. sent, bounced, etc).

header Parameters

x-cio-timestamp required	integer <unix timestamp> The timestamp when the request was sent.
x-cio-signature required	string A string combining your webhook signing key with the body of webhook request using an HMAC-SHA256 hash, used to help you securely verify requests.

Request Body: application/json

One of

metric required	string Value: "subscribed" The metric recorded by the event. For `customer` events, this is whether the customer explicitly subscribed or unsubscribed.
event_id required	string The unique identifier for the event.
object_type required	string Value: "customer" The event represents a customer subscribing, unsubscribing, or changing their subscription preferences.
timestamp required	integer <unix timestamp> The unix timestamp when the event occurred.
required	object Contains information about the event, specific to the `object_type` and `metric`.

Request samples

Payload

Content type

application/json

Example

{"metric": "subscribed",
"event_id": "01E4C4CT6YDC7Y5M7FE1GWWPQJ",
"object_type": "customer",
"timestamp": 1613063089,
"data": {"customer_id": "42",
"email_address": "test@example.com",
"identifiers": {"id": "42",
"email": "test@example.com",
"cio_id": "d9c106000001"
}
}
}

Customer Events

Customer events occur when a a person changes their subscription settings—their unsubscribed or cio_subscription_preferences attributes change. These changes happen without a reference to a message—like when a customer changes a subscription preference in their account information.

Customer subscribed

A person subscribed to messages from you—their unsubscribed attribute was set to false.

metric required	string Value: "subscribed" The metric recorded by the event. For `customer` events, this is whether the customer explicitly subscribed or unsubscribed.
event_id required	string The unique identifier for the event.
object_type required	string Value: "customer" The event represents a customer subscribing, unsubscribing, or changing their subscription preferences.
timestamp required	integer <unix timestamp> The unix timestamp when the event occurred.
required	object Contains information about the event, specific to the `object_type` and `metric`.

{"metric": "subscribed",
"event_id": "01E4C4CT6YDC7Y5M7FE1GWWPQJ",
"object_type": "customer",
"timestamp": 1613063089,
"data": {"customer_id": "42",
"email_address": "test@example.com",
"identifiers": {"id": "42",
"email": "test@example.com",
"cio_id": "d9c106000001"
}
}
}

Customer Unsubscribed

A person unsubscribed to messages from you—their unsubscribed attribute was set to true.

metric required	string Value: "unsubscribed" The metric recorded by the event. For `customer` events, this is whether the customer explicitly subscribed or unsubscribed.
event_id required	string The unique identifier for the event.
object_type required	string Value: "customer" The event represents a customer subscribing, unsubscribing, or changing their subscription preferences.
timestamp required	integer <unix timestamp> The unix timestamp when the event occurred.
required	object Contains information about the event, specific to the