Customer.io Messages API
Retrieve information about individual messages sent to customers.
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OpenAPI Specification
openapi: 3.2.0
info:
version: 1.0.0
title: Customer.io App Messages API
description: 'Our App API provides ways to trigger messages and retrieve information about people, campaigns, broadcasts, and more.
# Overview
The App API provides methods to send newsletters, transactional messages, and API-triggered broadcasts. You can create newsletters from scratch and update transactional messages and API-triggered broadcasts.
For transactional messages and API-triggered broadcasts, your payload acts as a message "trigger" and can contain `data` that you reference in your messages using liquid—`{{trigger.<data>}}`.
The other endpoints help you retrieve information about people, segments, campaigns, broadcasts, etc; it also lets you update campaign actions, messages, newsletter variants, etc. Aside from the [API-triggered broadcast](#triggerBroadcast) (1 per 10 seconds) and [Transactional](#sendEmail) (100 per second) endpoints, requests are limited to 10 per second.
# Use our Postman collection
We''ve generated a Postman collection to help you get started with our APIs.
If you fork this collection, you might want to disable the *Watch original collection* option. We automatically update our Postman collection whenever we release changes to our documentation, even if we don''t change our APIs—which happens daily! Rather than being flooded with Postman notifications, you can check out our [Release Notes](/release-notes/) for updates to our APIs.
**NOTE**: Postman endpoints default to our US APIs. If you''re in our European (EU) region, you''ll need to add `-eu` to the server variables (`track_api_url` and `app_api_url`).
[<img src="https://run.pstmn.io/button.svg" alt="Run In Postman" style="width: 128px; height: 32px;">](https://god.gw.postman.com/run-collection/23697545-2931c004-e63d-4cdc-bf4b-e685ba6da42d?action=collection%2Ffork&source=rip_markdown&collection-url=entityId%3D23697545-2931c004-e63d-4cdc-bf4b-e685ba6da42d%26entityType%3Dcollection%26workspaceId%3Db886877f-fc09-475f-84fe-6221a98f4d18#?env%5BCustomer.io%20API%20Environment%5D=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)
# Server addresses: US and EU
Customer.io hosts services in the United States (US) and European Union. Select the appropriate server address for your region.
| Region | Server Address |
| :-- | :-- |
| US | https://api.customer.io |
| EU | https://api-eu.customer.io |
# Authentication
All requests to the Customer.io App API use an [App API Key](#App-API-Key).
To authenticate, provide your key as a Bearer token in a HTTP Authorization header. You can create and manage your API keys—including keys with different scopes—in [your account settings page](https://fly.customer.io/settings/api_credentials?keyType=app). Each operation on this page references the authorization header it requires.
# Rate Limits
Most endpoints on this page are limited to 10 requests per second. The exceptions are:
* The [transactional email](#operation/sendEmail) endpoint is limited to 100 requests per second.
* The [API-triggered broadcast endpoint](#operation/triggerBroadcast) is limited to 1 request every 10 seconds.
**Rate limits are subject to change. We may adjust these thresholds to ensure stable performance for all customers.**
'
servers:
- url: https://api.customer.io
description: The base URL for broadcasts, transactional messages, and data-retrieval APIs. These endpoints use bearer authorization, and require a [token that you generate in the UI](https://fly.customer.io/settings/api_credentials?keyType=app).
- url: https://api-eu.customer.io
description: The base URL for broadcasts, transactional messages, and data-retrieval APIs (EU region). These endpoints use bearer authorization, and require a [token that you generate in the UI](https://fly.customer.io/settings/api_credentials?keyType=app).
tags:
- name: Messages
description: 'Return information about message and webhook "deliveries"—the instance of a message or webhook intended for an individual recipient.
'
paths:
/v1/messages:
servers:
- url: https://api.customer.io
description: This API uses bearer authorization, requiring a [token that you generate in the UI](https://fly.customer.io/settings/api_credentials?keyType=app).
parameters:
- name: start
in: query
required: false
description: The token for the page of results you want to return. Responses contain a `next` property. Use this property as the `start` value to return the next page of results.
schema:
type: string
- name: limit
in: query
required: false
description: The maximum number of results you want to retrieve per page.
schema:
type: integer
default: 50
maximum: 1000
- name: type
in: query
required: false
description: The type of item you want to return metrics for. When empty, the response contains metrics for all possible types.
schema:
type: string
enum:
- email
- webhook
- twilio
- whatsapp
- slack
- push
- in_app
- live_notification
- name: metric
in: query
required: false
description: Determines the metric(s) you want to return.
schema:
type: string
enum:
- attempted
- sent
- delivered
- opened
- clicked
- converted
- bounced
- spammed
- unsubscribed
- dropped
- failed
- undeliverable
- name: drafts
in: query
required: false
description: If true, your request returns drafts rather than active/sent messages.
schema:
type: boolean
- name: campaign_id
in: query
required: false
description: The campaign you want to filter for.
schema:
type: integer
- name: newsletter_id
in: query
required: false
description: The newsletter you want to filter for.
schema:
type: integer
- name: action_id
in: query
required: false
description: The action you want to filter for.
schema:
type: integer
- name: start_ts
in: query
required: false
description: The beginning timestamp for your query.
schema:
type: integer
format: unix timestamp
- name: end_ts
in: query
required: false
description: The ending timestamp for your query.
schema:
type: integer
format: unix timestamp
- name: get_tracked_responses
in: query
required: false
description: If true, the response includes `tracked_responses` for each message—an object containing tracked response option names for in-app survey responses.
schema:
type: boolean
default: false
get:
summary: List messages
operationId: listMessages
security:
- Bearer-Auth: []
description: 'Return a list of deliveries, including metrics for each delivery, for messages in your workspace. The request body contains filters determining the deliveries you want to return information about.
Use the `start_ts` and `end_ts` parameters to find messages within a time range. We limit your requests to 6 months. If your request doesn''t include `start_ts` and `end_ts` parameters, we''ll return the most recent 6 months of deliveries. If `start_ts` is greater than 6-months before `end_ts`, we only send back 6 months of data. If only `end_ts` is specified, we return 6 months of data before this timestamp. If only `start_ts` is specified, we then set the `end_ts` to the current time and deliver 6 months of data prior to this timestamp. Timestamps reflect when deliveries were created in our system, not when they were actually sent to recipients. There may be a delay between creation and sending.
'
tags:
- Messages
responses:
'200':
description: Returns an array of message objects.
content:
application/json:
schema:
type: object
properties:
messages:
type: array
description: Each object in the array describes an individual message delivery. The object contains keys for all possible parents of the message (`newsletter_id`, `broadcast_id`, etc) but only the parents of the delivery are populated. Other parent IDs are null.
items:
x-scalar-ignore: true
description: Describes an individual message delivery. The object contains keys for all possible parents of the message (`newsletter_id`, `broadcast_id`, etc) but only the parents of the delivery are populated. Other parent IDs are null.
allOf:
- x-scalar-ignore: true
type: object
description: Describes an individual message delivery. The object contains keys for all possible parents of the message (`newsletter_id`, `broadcast_id`, etc) but only the parents of the delivery are populated. Other parent IDs are null.
properties:
id:
x-scalar-ignore: true
description: The identifier for a delivery—the instance of a message intended for an individual recipient.
type: string
readOnly: true
example: dgOq6QWq6QUBAAF4_CGoeVX7mFkDbRFu7ek=
deduplicate_id:
x-scalar-ignore: true
type: string
readOnly: true
description: An identifier in the format `id:timestamp` where the id is for the object you're working with (Campaigns, Deliveries, Exports, Identities, Newsletters, Segments, and Templates), and the timestamp is the last time the object was updated.
example: 15:1492548073
message_template_id:
x-scalar-ignore: true
description: The identifier of the message template used to create a message.
type: integer
readOnly: true
deprecated: true
customer_id:
x-scalar-ignore: true
type:
- string
- 'null'
description: The ID of a customer profile, analogous to a "person" in the UI. If your workspace supports multiple identifiers (email and ID), this value can be null.
example: '42'
customer_identifiers:
x-scalar-ignore: true
type: object
description: Identifiers for the person in a response—`id`, `cio_id`, and `email`. Unset `id` or `email` values are `null`. We recommend this object over the less descriptive `customer_id`. This object doesn't include `phone`, even if your workspace uses phone numbers as an identifier; look for the person's `phone` attribute instead.
required:
- email
- id
- cio_id
properties:
email:
type:
- string
- 'null'
format: email
description: A person's email address, if set.
example: test@example.com
id:
type:
- string
- 'null'
description: A person's unique ID, if set. This is the same as the `customer_id` if present.
example: 2
cio_id:
x-scalar-ignore: true
type: string
description: A unique identifier set by Customer.io, used to reference a person if you want to update their identifiers.
example: a3000001
recipient:
x-scalar-ignore: true
description: The recipient address for an action.
type: string
example: '{{customer.email}}'
subject:
x-scalar-ignore: true
type: string
description: The subject line for an `email` action.
example: Did you get that thing I sent you?
metrics:
x-scalar-ignore: true
type: object
description: Metrics for an individual instance of a message; each item in the object represents the timestamp when a message achieved a particular metric. This object only contains metrics that have been recorded.
properties:
bounced:
type: integer
description: The timestamp when the message `bounced`.
clicked:
type: integer
description: The timestamp when the message was `clicked`.
human_clicked:
type: integer
description: The number of `clicked` messages excluding machine clicks. This metric is reliable starting April 20, 2025. [Learn more](/journeys/metrics/analytics/#delivery-metrics).
prefetch_clicked:
type: integer
description: The number of `clicked` messages attributed to machines. This metric is reliable starting April 20, 2025.
converted:
type: integer
description: The timestamp when the message was `converted`.
created:
type: integer
description: The timestamp when the message was `created`.
delivered:
type: integer
description: The timestamp when the message was `delivered`.
drafted:
type: integer
description: The timestamp when the message was `drafted`.
dropped:
type: integer
description: The timestamp when the message was `dropped`.
failed:
type: integer
description: The timestamp when the message `failed`.
opened:
type: integer
description: The timestamp when the message was `opened`.
human_opened:
type: integer
description: The number of `opened` messages excluding machine opens. This metric is reliable starting March 20, 2025. [Learn more](/journeys/metrics/analytics/#delivery-metrics).
prefetch_opened:
type: integer
description: The number of `opened` messages attributed to machines. This metric is reliable starting March 20, 2025.
sent:
type: integer
description: The timestamp when the message was `sent`.
spammed:
type: integer
description: The timestamp when the message was marked as spam.
undeliverable:
type: integer
description: The timestamp when the message became `undeliverable`.
unsubscribed:
type: integer
description: The timestamp when a person unsubscribed based on this message.
created:
x-scalar-ignore: true
type: integer
format: unix timestamp
description: The date time when the referenced ID was created.
example: 1552341937
readOnly: true
failure_message:
type:
- string
- 'null'
description: Explains why a message failed, if applicable.
campaign_id:
oneOf:
- x-scalar-ignore: true
description: The identifier for a campaign.
type: integer
example: 5
- type: 'null'
action_id:
x-scalar-ignore: true
description: The identifier for an action.
type: integer
readOnly: true
example: 96
parent_action_id:
x-scalar-ignore: true
type: integer
description: The ID of the parent action, if the action occurred within a campaign and has a parent (like a randomized split, etc).
example: 1
readOnly: true
newsletter_id:
oneOf:
- x-scalar-ignore: true
description: The identifier for a newsletter.
type: integer
example: 10
- type: 'null'
content_id:
x-scalar-ignore: true
description: The identifier for a message in a newsletter. Newsletters can have multiple content IDs (for multi-language messages or A/B tests).
type: integer
readOnly: true
example: 1
broadcast_id:
oneOf:
- x-scalar-ignore: true
type: integer
description: The identifier for a broadcast.
example: 2
- type: 'null'
trigger_event_id:
x-scalar-ignore: true
type: string
description: The id of the event that triggered an event-triggered campaign (not an API-triggered broadcast).
example: 21E4C3CT6YDC7Y4N7FE1GWWABC
forgotten:
type: boolean
description: If true message contents are not retained by Customer.io.
tracked_responses:
type: object
description: Tracked in-app survey responses, keyed by response option name. Present only when `get_tracked_responses` is `true`.
additionalProperties:
type: object
properties:
id:
type: integer
description: The identifier for the tracked response.
ts:
type: integer
description: A unix timestamp representing when the response was tracked.
example:
cool-button:
id: 1
ts: 1715769600
cool-button-2:
id: 2
ts: 1715769600
- type: object
properties:
type:
x-scalar-ignore: true
description: The type of message or action for a delivery, campaign action, or related object. Includes channels that newsletters do not support (for example, `slack` and `whatsapp`).
type: string
enum:
- email
- webhook
- twilio
- push
- in_app
- slack
- whatsapp
- live_notification
readOnly: true
example: email
example:
id: ag1q6QWq6QUBAAF4_CGoeVX7mFkDbRFu7ek=
deduplicate_id: ag1q6QWq6QUBAAF4_CGoeVX7mFkDbRFu7ek=:1619137768
msg_template_id: 43
action_id: 215
parent_action_id: null
customer_id: null
recipient: person@example.com
subject: Did you get that thing I sent you?
metrics:
delivered: 1619137768
sent: 1619137768
created: 1619137767
failure_message: null
newsletter_id: null
content_id: null
campaign_id: 23
broadcast_id: null
trigger_event_id: null
type: email
forgotten: false
examples:
email:
summary: An email message
value:
messages:
- id: ag1q6QWq6QUBAAF4_CGoeVX7mFkDbRFu7ek=
deduplicate_id: ag1q6QWq6QUBAAF4_CGoeVX7mFkDbRFu7ek=:1619137768
msg_template_id: 43
action_id: 215
parent_action_id: null
customer_id: null
recipient: person@example.com
subject: Did you get that thing I sent you?
metrics:
delivered: 1619137768
sent: 1619137768
created: 1619137767
failure_message: null
newsletter_id: null
content_id: null
campaign_id: 23
broadcast_id: null
trigger_event_id: null
type: email
forgotten: false
in-app:
summary: An in-app message with tracked survey responses
value:
messages:
- id: bX2r7YZq8RCAAB5_DGopeWY8nGlEcSGv8fl=
deduplicate_id: bX2r7YZq8RCAAB5_DGopeWY8nGlEcSGv8fl=:1715769500
msg_template_id: 87
action_id: 312
parent_action_id: null
customer_id: user_2048
recipient: user_2048
subject: null
metrics:
opened: 1715769550
sent: 1715769500
created: 1715769500
failure_message: null
newsletter_id: null
content_id: null
campaign_id: 45
broadcast_id: null
trigger_event_id: null
type: in_app
forgotten: false
tracked_responses:
how-satisfied:
id: 1
ts: 1715769560
would-recommend:
id: 2
ts: 1715769565
'400':
description: The request was malformed.
'429':
description: Your request is over the 10-per-second limit.
x-codeSamples:
- lang: Shell + Curl
source: "curl --request GET \\\n --header 'Authorization: Bearer REPLACE_BEARER_TOKEN' \\\n --url https://api.customer.io/v1/messages"
- lang: Node + Native
source: "const http = require(\"https\");\n\nconst options = {\n \"method\": \"GET\",\n \"hostname\": \"api.customer.io\",\n \"port\": null,\n \"path\": \"/v1/messages\",\n \"headers\": {}\n};\n\nconst req = http.request(options, function (res) {\n const chunks = [];\n\n res.on(\"data\", function (chunk) {\n chunks.push(chunk);\n });\n\n res.on(\"end\", function () {\n const body = Buffer.concat(chunks);\n console.log(body.toString());\n });\n});\n\nreq.end();"
- lang: Ruby + Native
source: 'require ''uri''
require ''net/http''
require ''openssl''
url = URI("https://api.customer.io/v1/messages")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE
request = Net::HTTP::Get.new(url)
response = http.request(request)
puts response.read_body'
- lang: Python + Python3
source: 'import http.client
conn = http.client.HTTPSConnection("api.customer.io")
conn.request("GET", "/v1/messages")
res = conn.getresponse()
data = res.read()
print(data.decode("utf-8"))'
- lang: Go + Native
source: "package main\n\nimport (\n\t\"fmt\"\n\t\"net/http\"\n\t\"io/ioutil\"\n)\n\nfunc main() {\n\n\turl := \"https://api.customer.io/v1/messages\"\n\n\treq, _ := http.NewRequest(\"GET\", url, nil)\n\n\tres, _ := http.DefaultClient.Do(req)\n\n\tdefer res.Body.Close()\n\tbody, _ := ioutil.ReadAll(res.Body)\n\n\tfmt.Println(res)\n\tfmt.Println(string(body))\n\n}"
/v1/messages/{message_id}:
servers:
- url: https://api.customer.io
description: This API uses bearer authorization, requiring a [token that you generate in the UI](https://fly.customer.io/settings/api_credentials?keyType=app).
parameters:
- name: message_id
in: path
required: true
description: The identifier of a message.
schema:
type: string
- name: get_tracked_responses
in: query
required: false
description: If true, the response includes `tracked_responses` for each message—an object containing tracked response option names for in-app survey responses.
schema:
type: boolean
default: false
get:
summary: Get a message
operationId: getMessage
security:
- Bearer-Auth: []
description: Return a information about, and metrics for, a delivery—the instance of a message intended for an individual recipient person.
tags:
- Messages
responses:
'200':
description: Returns a message object.
content:
application/json:
schema:
type: object
description: Describes an individual message delivery. The object contains keys for all possible parents of the message (`newsletter_id`, `broadcast_id`, etc) but only the parents of the delivery are populated. Other parent IDs are null.
properties:
message:
x-scalar-ignore: true
description: Describes an individual message delivery. The object contains keys for all possible parents of the message (`newsletter_id`, `broadcast_id`, etc) but only the parents of the delivery are populated. Other parent IDs are null.
allOf:
- x-scalar-ignore: true
type: object
description: Describes an individual message delivery. The object contains keys for all possible parents of the message (`newsletter_id`, `broadcast_id`, etc) but only the parents of the delivery are populated. Other parent IDs are null.
properties:
id:
x-scalar-ignore: true
description: The identifier for a delivery—the instance of a message intended for an individual recipient.
type: string
readOnly: true
example: dgOq6QWq6QUBAAF4_CGoeVX7mFkDbRFu7ek=
deduplicate_id:
x-scalar-ignore: true
type: string
readOnly: true
description: An identifier in the format `id:timestamp` where the id is for the object you're working with (Campaigns, Deliveries, Exports, Identities, Newsletters, Segments, and Templates), and the timestamp is the last time the object was updated.
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# Full source: https://raw.githubusercontent.com/api-evangelist/customer-io/refs/heads/main/openapi/customer-io-messages-api-openapi.yml