Customer.io Newsletter Metrics API

openapi: 3.2.0
info:
  version: 1.0.0
  title: Customer.io App Newsletter Metrics 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: Newsletter Metrics
  description: 'Newsletter metrics include metrics for translations, A/B tests, and links.


    These endpoints return information about newsletter metrics including metrics for translations and A/B tests. You can update variants in newsletters from these endpoints, but you must perform all other create, update, and/or delete operations through the UI.

    '
paths:
  /v1/newsletters/{newsletter_id}/metrics:
    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: newsletter_id
      in: path
      required: true
      description: The identifier of a newsletter.
      schema:
        type: integer
    - name: period
      in: query
      required: false
      description: The unit of time for your report.
      schema:
        type: string
        default: days
        enum:
        - hours
        - days
        - weeks
        - months
    - name: steps
      in: query
      required: false
      description: The number of periods you want to return. Defaults to the maximum available, or `12` if the period is in `months`. Maximums are 24 hours, 45 days, 12 weeks, or 121 months. Days start at 00:00 EST. Weeks start at 00:00 EST on Sunday. Months start at 00:00 EST on the 1st of the month.
      schema:
        type: integer
    - 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
        - push
        - in_app
        - inbox
    get:
      summary: Get newsletter metrics
      operationId: getNewsletterMetrics
      security:
      - Bearer-Auth: []
      description: 'Returns a list of metrics for an individual newsletter in `steps` (days, weeks, etc). We return metrics from oldest to newest (i.e. the 0-index for any result is the oldest step/period).


        You cannot request fewer than 2 steps of any period (2 hours, 2 days, 2 weeks, or 2 months). For instance, `?period=days&steps=1` means two days - the 48 hours before the API request was made. `?period=days&steps=0` returns the same as the maximum of the period - `?period=days&steps=45`. See the `steps` parameter below for the maximum count of each period.

        '
      tags:
      - Newsletter Metrics
      responses:
        '200':
          description: Returns newsletter metrics by `series` (with increments are based on the `period` and `step` in your request) for the newsletter.
          content:
            application/json:
              schema:
                type: object
                properties:
                  metric:
                    type: object
                    properties:
                      type:
                        x-scalar-ignore: true
                        description: Channel type for a newsletter or newsletter content variant.
                        type: string
                        enum:
                        - email
                        - webhook
                        - twilio
                        - push
                        - in_app
                        - inbox
                        readOnly: true
                        example: email
                      series:
                        allOf:
                        - x-scalar-ignore: true
                          type: object
                          description: Metrics grouped by the requested resolution. Each property is an array where each entry represents one period, such as one day.
                          properties:
                            2xx:
                              type: array
                              items:
                                type: integer
                              description: 2xx responses by period, representative of webhook performance.
                            3xx:
                              type: array
                              items:
                                type: integer
                              description: 3xx responses by period, representative of webhook performance.
                            4xx:
                              type: array
                              items:
                                type: integer
                              description: 4xx responses by period, representative of webhook performance.
                            5xx:
                              type: array
                              items:
                                type: integer
                              description: 5xx responses by period, representative of webhook performance.
                        - x-scalar-ignore: true
                          description: Metrics grouped by the requested resolution. Each property is an array where each entry represents one period, such as one day.
                          type: object
                          properties:
                            attempted:
                              type: array
                              items:
                                type: integer
                              description: The number of `attempted` messages.
                            bounced:
                              type: array
                              items:
                                type: integer
                              description: The number of `bounced` messages.
                            clicked:
                              type: array
                              items:
                                type: integer
                              description: The number of `clicked` messages.
                            human_clicked:
                              type: array
                              items:
                                type: integer
                              description: The number of `clicked` emails excluding machine clicks. This metric is reliable starting April 20, 2025. [Learn more](/journeys/metrics/analytics/#delivery-metrics).
                            prefetch_clicked:
                              type: array
                              items:
                                type: integer
                              description: The number of `clicked` emails attributed to machines. This metric is reliable starting April 20, 2025.
                            converted:
                              type: array
                              items:
                                type: integer
                              description: The number of `converted` messages.
                            created:
                              type: array
                              items:
                                type: integer
                              description: The number of `created` messages.
                            deferred:
                              type: array
                              items:
                                type: integer
                              description: The number of `deferred` messages.
                            delivered:
                              type: array
                              items:
                                type: integer
                              description: The number of `delivered` messages.
                            drafted:
                              type: array
                              items:
                                type: integer
                              description: The number of `drafted` messages.
                            failed:
                              type: array
                              items:
                                type: integer
                              description: The number of `failed` messages.
                            opened:
                              type: array
                              items:
                                type: integer
                              description: The number of `opened` messages.
                            human_opened:
                              type: array
                              items:
                                type: integer
                              description: The number of `opened` emails excluding machine opens. This metric is reliable starting March 20, 2025. [Learn more](/journeys/metrics/analytics/#delivery-metrics).
                            prefetch_opened:
                              type: array
                              items:
                                type: integer
                              description: The number of `opened` emails attributed to machines. This metric is reliable starting March 20, 2025.
                            sent:
                              type: array
                              items:
                                type: integer
                              description: The number of sent messages.
                            spammed:
                              type: array
                              items:
                                type: integer
                              description: The number of spam complaints.
                            suppressed:
                              type: array
                              items:
                                type: integer
                              description: The number of `suppressed` messages.
                            undeliverable:
                              type: array
                              items:
                                type: integer
                              description: The number of `undeliverable` messages.
                            topic_unsubscribed:
                              type: array
                              items:
                                type: integer
                              description: The number of topic unsubscribes in a given period.
                            unsubscribed:
                              type: array
                              items:
                                type: integer
                              description: The number of unsubscribes attributed to the campaign or message.
        '404':
          description: The newsletter you requested does not exist.
        '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/newsletters/{newsletter_id}/metrics"
      - 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/newsletters/%7Bnewsletter_id%7D/metrics\",\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/newsletters/%7Bnewsletter_id%7D/metrics")


          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/newsletters/%7Bnewsletter_id%7D/metrics")


          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/newsletters/%7Bnewsletter_id%7D/metrics\"\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/newsletters/{newsletter_id}/metrics/links:
    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: newsletter_id
      in: path
      required: true
      description: The identifier of a newsletter.
      schema:
        type: integer
    - name: period
      in: query
      required: false
      description: The unit of time for your report.
      schema:
        type: string
        default: days
        enum:
        - hours
        - days
        - weeks
        - months
    - name: steps
      in: query
      required: false
      description: The number of periods you want to return. Defaults to the maximum available, or `12` if the period is in `months`. Maximums are 24 hours, 45 days, 12 weeks, or 121 months. Days start at 00:00 EST. Weeks start at 00:00 EST on Sunday. Months start at 00:00 EST on the 1st of the month.
      schema:
        type: integer
    - name: unique
      in: query
      required: false
      description: If true, the response contains only unique customer results, i.e. a customer who clicks a link twice is only counted once. If false, the response contains the total number of results without regard to uniqueness.
      schema:
        type: boolean
        default: false
    get:
      summary: Get click metrics for newsletter links
      operationId: getNewsletterLinks
      security:
      - Bearer-Auth: []
      description: 'Returns metrics for link clicks within a newsletter, both in total and in `series` periods (days, weeks, etc). `series` metrics are ordered oldest to newest (i.e. the 0-index for any result is the oldest step/period).


        You cannot request fewer than 2 steps of any period (2 hours, 2 days, 2 weeks, or 2 months). For instance, `?period=days&steps=1` means two days - the 48 hours before the API request was made. `?period=days&steps=0` returns the same as the maximum of the period - `?period=days&steps=45`. See the `steps` parameter below for the maximum count of each period.

        '
      tags:
      - Newsletter Metrics
      responses:
        '200':
          description: Returns an array of link objects. Each object represents a different link in your newsletter and contains independent metrics.
          content:
            application/json:
              schema:
                type: object
                properties:
                  links:
                    type: array
                    items:
                      x-scalar-ignore: true
                      type: object
                      properties:
                        link:
                          type: object
                          properties:
                            id:
                              type: integer
                              description: The ID of the link.
                              example: 1234
                            href:
                              type: string
                              description: The link destination—a URL, mailto, etc.
                              example: https://docs.customer.io
                        metric:
                          type: object
                          description: Contains metrics for the link.
                          properties:
                            series:
                              type: object
                              properties:
                                clicked:
                                  type: array
                                  description: An array of results from oldest to newest, where each result indicates a period.
                                  items:
                                    type: integer
                                  example:
                                  - 1
                                  - 3
                                  - 5
                                  - 7
                                human_clicked:
                                  type: array
                                  description: An array of human click counts (clicks excluding machine clicks) from oldest to newest, where each result indicates a period. This metric is reliable starting April 20, 2025. [Learn more](/journeys/metrics/analytics/#delivery-metrics).
                                  items:
                                    type: integer
                                  example:
                                  - 1
                                  - 2
                                  - 3
                                  - 4
                                machine_clicked:
                                  type: array
                                  description: An array of machine click counts (clicks attributed to bots or prefetching) from oldest to newest, where each result indicates a period. This metric is reliable starting April 20, 2025. [Learn more](/journeys/metrics/analytics/#delivery-metrics).
                                  items:
                                    type: integer
                                  example:
                                  - 0
                                  - 1
                                  - 1
                                  - 2
        '404':
          description: The newsletter you requested does not exist.
        '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/newsletters/{newsletter_id}/metrics/links"
      - 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/newsletters/%7Bnewsletter_id%7D/metrics/links\",\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/newsletters/%7Bnewsletter_id%7D/metrics/links")


          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/newsletters/%7Bnewsletter_id%7D/metrics/links")


          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/newsletters/%7Bnewsletter_id%7D/metrics/links\"\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/newsletters/{newsletter_id}/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: newsletter_id
      in: path
      required: true
      description: The identifier of a newsletter.
      schema:
        type: integer
    - 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
    - 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: 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: Get delivery data for a newsletter
      operationId: getNewsletterMsgMeta
      security:
      - Bearer-Auth: []
      description: 'Returns information about the "deliveries" (rendered messages) sent to your recipients for a specific newsletter.


        Provide query parameters to refine the metrics you want to return. Use `start_ts` and `end_ts` to find messages within a time range. If your request doesn''t include `start_ts` and `end_ts` parameters, we''ll return up to 6 months of results beginning with the first delivery generated from the newsletter. If your `start_ts` and `end_ts` range is more than 12 months, we''ll return 12 months of data from the most recent timestamp in your request.


        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:
      - Newsletter Metrics
      responses:
        '200':
          description: Returns an array of `messages`. Each object represents a different delivery to a recipient.
          content:
            application/json:
              schema:
                type: object
                properties:
                  messages:
                    type: array
                    items:
                      x-scalar-ignore: true
                      description: Each object is a delivery of a newsletter.
                      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
       

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# Full source: https://raw.githubusercontent.com/api-evangelist/customer-io/refs/heads/main/openapi/customer-io-newsletter-metrics-api-openapi.yml