Customer.io

Connect & Ingest data from Customer.io

Customer.io is a customer engagement platform that enables businesses to send automated emails, push notifications, SMS, and in-app messages based on user behavior. The Sling Customer.io connector extracts data from the Customer.io App API, supporting campaigns, broadcasts, newsletters, segments, activities, messages, and more.

CLI Pro Required: APIs require a CLI Pro token or Platform Plan.

Setup

The following credentials and inputs are accepted:

Secrets:

• app_api_key (required) -> Your Customer.io App API Key

Inputs (optional):

• base_url (optional) -> API base URL. Use https://api-eu.customer.io for EU region. Defaults to https://api.customer.io.

• anchor_date (optional) -> Starting date for first sync in ISO 8601 format (e.g., 2024-01-01T00:00:00Z). Defaults to 1 year ago.

Getting Your API Key

1. Log in to your Customer.io account

2. Go to Settings > Account Settings > API Credentials

3. Click the App API keys tab

4. Click Create App API Key

5. Give the key a name (e.g., "Sling Integration")

6. Click Create and copy the key immediately — it is only shown once

Important: Use an App API Key, not a Track API Key. Track API keys are for sending data to Customer.io, while App API keys are for reading data from Customer.io.

Using sling conns

sling conns set CUSTOMERIO type=api spec=customerio secrets='{ app_api_key: "your_app_api_key_here" }'

Environment Variable

See here to learn more about the .env.sling file.

export CUSTOMERIO='{ type: api, spec: customerio, secrets: { app_api_key: "your_app_api_key_here" } }'

Sling Env File YAML

See here to learn more about the sling env.yaml file.

connections:
  CUSTOMERIO:
    type: api
    spec: customerio
    secrets:
      app_api_key: "your_app_api_key_here"

EU Region

If your Customer.io workspace is hosted in the EU data center, add the base_url input:

connections:
  CUSTOMERIO:
    type: api
    spec: customerio
    secrets:
      app_api_key: "your_app_api_key_here"
    inputs:
      base_url: "https://api-eu.customer.io"

Replication

Here's an example replication configuration to sync Customer.io data to a PostgreSQL database:

source: CUSTOMERIO
target: MY_POSTGRES

defaults:
  mode: full-refresh
  object: customerio.{stream_name}

streams:
  # Core messaging data
  campaigns:
  campaign_actions:
  broadcasts:
  broadcast_actions:
  newsletters:

  # Audience data
  segments:
  segment_membership:

  # Activity and message data (incremental)
  activities:
    mode: incremental
  messages:
    mode: incremental

  # Reference data
  transactional_messages:
  collections:
  snippets:
  sender_identities:
  subscription_topics:

Endpoints

Messaging

Endpoint	Description	Incremental
campaigns	Campaign definitions and metadata	No
campaign_actions	Actions/steps within each campaign (child of campaigns)	No
broadcasts	One-time broadcast messages	No
broadcast_actions	Actions within each broadcast (child of broadcasts)	No
newsletters	Newsletter definitions	No
transactional_messages	Transactional message templates	No

Audience

Endpoint	Description	Incremental
segments	Audience segment definitions	No
segment_membership	Customer IDs in each segment (child of segments)	No

Activity & Messages

Endpoint	Description	Incremental
activities	Activity log (attribute changes, events, message sends)	Yes (cursor)
messages	Message delivery records (max 6 months lookback)	Yes (timestamp)

Reference Data

Endpoint	Description	Incremental
collections	Data collections for personalization	No
snippets	Reusable content snippets	No
sender_identities	Sender email identities	No
subscription_topics	Subscription preference topics	No

To discover available endpoints:

sling conns discover CUSTOMERIO

Parent-Child Endpoints

Some endpoints are children of parent endpoints and require the parent to run first:

• campaign_actions -> Requires campaigns to run first (iterates through each campaign)

• broadcast_actions -> Requires broadcasts to run first (iterates through each broadcast)

• segment_membership -> Requires segments to run first (iterates through each segment)

When using these endpoints in a replication, Sling automatically handles the ordering via internal queues.

Incremental Sync

The Customer.io connector supports incremental sync for the following endpoints:

• activities - Uses cursor-based pagination to resume from the last position

• messages - Uses timestamp-based filtering with start_ts and end_ts parameters (maximum 6 months lookback)

How it works

• First run: Fetches all available data (activities) or the last 6 months (messages)

• Subsequent runs: Only fetches records created after the last sync position

Rate Limiting

The Customer.io App API enforces a rate limit of 10 requests per second. The connector automatically:

• Limits to 10 requests/second

• Limits concurrency to 3 parallel requests

• Retries with exponential backoff on 429 (rate limit) responses

If you are facing issues connecting, please reach out to us at [email protected], on discord or open a Github Issue here.