eusend-dev Topics API

openapi: 3.2.0
info:
  title: eusend Topics API
  version: 1.0.0
  summary: EU-native transactional and marketing email API.
  description: 'eusend sends transactional and marketing email from infrastructure that stays inside the European Union — processing, storage and delivery alike.


    **When to use this API.** Reach for eusend to send application email from server-side code: password resets, receipts, verification codes, notifications, and opt-in marketing broadcasts to a list you own. It is a good fit when GDPR or EU data residency is a requirement, when you are migrating off Resend, SendGrid, Mailgun, Postmark or SES, or when you need SMTP relay rather than an HTTP call. It is not a fit for inbox hosting, for reading a user’s mailbox, or for sending to purchased or scraped lists.


    **Getting started.** Create an account, verify a sending domain by publishing the DNS records the domain endpoints hand back, then `POST /emails`. A key prefixed `eu_test_` exercises the whole pipeline without delivering anything.


    **Authentication.** Every authenticated endpoint takes `Authorization: Bearer `. Keys are `eu_live_…` or `eu_test_…`, and carry either `full_access` or the send-only `sending_access` permission.


    **Errors.** Non-2xx responses are always `{ "error": string, "code": string }`. Branch on `code`; the list is enumerated on the `Error` schema.


    **Conventions.** Request bodies use snake_case and reject unknown properties. Response bodies use camelCase, except the pagination cursor and a handful of endpoints noted inline. List endpoints are cursor-paginated, newest first. Every response carries `X-Request-Id`.'
  termsOfService: https://eusend.dev/legal/terms
  contact:
    name: eusend support
    email: support@eusend.dev
    url: https://eusend.dev/support
  license:
    name: Proprietary
    url: https://eusend.dev/legal/terms
servers:
- url: https://api.eusend.dev
  description: Production
security:
- bearerAuth: []
tags:
- name: Topics
  description: Kinds of email a contact can subscribe to and leave independently, so an unsubscribe can be a preference change.
paths:
  /topics:
    post:
      operationId: createTopic
      summary: Create a topic
      description: A topic is a kind of email a contact can subscribe to and leave independently of the audience they sit on, so an unsubscribe becomes a preference change rather than losing the contact. The default subscription is fixed at creation.
      tags:
      - Topics
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateTopicRequest'
      responses:
        '201':
          description: Created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Topic'
        '400':
          description: The request body or query failed validation (`VALIDATION_ERROR`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '409':
          description: A topic with that name already exists (`CONFLICT`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Rate limit exceeded (`RATE_LIMITED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
    get:
      operationId: listTopics
      summary: List topics
      description: Every topic the organization has defined, by name, with the number of contacts explicitly opted in to each. Unpaginated — the list is capped at 100 entries.
      tags:
      - Topics
      responses:
        '200':
          description: The topics.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ListTopicsResponse'
        '401':
          description: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Rate limit exceeded (`RATE_LIMITED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /topics/{id}:
    get:
      operationId: getTopic
      summary: Get a topic
      description: One topic by id.
      tags:
      - Topics
      parameters:
      - name: id
        in: path
        required: true
        description: The topic id.
        schema:
          type: string
          format: uuid
      responses:
        '200':
          description: The topic.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Topic'
        '401':
          description: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: No such resource on this organization (`NOT_FOUND`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Rate limit exceeded (`RATE_LIMITED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
    patch:
      operationId: updateTopic
      summary: Update a topic
      description: 'Name, description and visibility. `default_subscription` is rejected: it is a consent decision, and changing it would start or stop mail for every contact who never chose.'
      tags:
      - Topics
      parameters:
      - name: id
        in: path
        required: true
        description: The topic id.
        schema:
          type: string
          format: uuid
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/UpdateTopicRequest'
      responses:
        '200':
          description: Updated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Topic'
        '400':
          description: The request body or query failed validation (`VALIDATION_ERROR`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: No such resource on this organization (`NOT_FOUND`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '409':
          description: Another topic already has this name (`CONFLICT`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Rate limit exceeded (`RATE_LIMITED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
    delete:
      operationId: deleteTopic
      summary: Delete a topic
      description: Deletes the topic and every stored preference for it. A draft broadcast scoped to it widens back to its whole audience; one that is scheduled, sending, paused or held blocks the delete. Broadcasts already sent keep their recipient records.
      tags:
      - Topics
      parameters:
      - name: id
        in: path
        required: true
        description: The topic id.
        schema:
          type: string
          format: uuid
      responses:
        '200':
          description: Deleted.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/DeleteTopicResponse'
        '401':
          description: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: No such resource on this organization (`NOT_FOUND`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '409':
          description: A broadcast scoped to this topic has not finished sending (`CONFLICT`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Rate limit exceeded (`RATE_LIMITED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /topics/{id}/contacts/{contactId}:
    put:
      operationId: setTopicSubscription
      summary: Set a contact's topic subscription
      description: Records an explicit preference, overriding the topic default.
      tags:
      - Topics
      parameters:
      - name: id
        in: path
        required: true
        description: The topic id.
        schema:
          type: string
          format: uuid
      - name: contactId
        in: path
        required: true
        description: The contact id.
        schema:
          type: string
          format: uuid
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TopicSubscriptionRequest'
      responses:
        '200':
          description: Saved.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TopicSubscriptionResponse'
        '400':
          description: The request body or query failed validation (`VALIDATION_ERROR`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: No such resource on this organization (`NOT_FOUND`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Rate limit exceeded (`RATE_LIMITED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
    delete:
      operationId: clearTopicSubscription
      summary: Clear a contact's topic subscription
      description: 'Forgets the explicit choice so the contact falls back to the topic default. Different from `subscribed: false`, which records a refusal — on an `opt_in` topic, clearing means the contact starts receiving it again.'
      tags:
      - Topics
      parameters:
      - name: id
        in: path
        required: true
        description: The topic id.
        schema:
          type: string
          format: uuid
      - name: contactId
        in: path
        required: true
        description: The contact id.
        schema:
          type: string
          format: uuid
      responses:
        '200':
          description: Cleared.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ClearTopicSubscriptionResponse'
        '401':
          description: Missing, malformed, or revoked API key (`UNAUTHORIZED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: The key exists but may not reach this resource — a `sending_access` key outside the send paths, a test-mode key writing live state, or an account on hold (`FORBIDDEN`, `ACCOUNT_RESTRICTED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: No such resource on this organization (`NOT_FOUND`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Rate limit exceeded (`RATE_LIMITED`).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Unexpected server error (`INTERNAL_ERROR`). Carries `request_id`.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
components:
  schemas:
    TopicSubscriptionRequest:
      type: object
      required:
      - subscribed
      additionalProperties: false
      properties:
        subscribed:
          type: boolean
    UpdateTopicRequest:
      type: object
      additionalProperties: false
      properties:
        name:
          type: string
          maxLength: 50
        description:
          type:
          - string
          - 'null'
          maxLength: 200
          description: Send `null` to clear it.
        visibility:
          type: string
          enum:
          - public
          - private
    ClearTopicSubscriptionResponse:
      type: object
      required:
      - topicId
      - contactId
      - deleted
      properties:
        topicId:
          type: string
          format: uuid
        contactId:
          type: string
          format: uuid
        deleted:
          type: boolean
    CreateTopicRequest:
      type: object
      required:
      - name
      - default_subscription
      additionalProperties: false
      properties:
        name:
          type: string
          maxLength: 50
          description: What the recipient reads on the unsubscribe page. Unique within the organization.
        default_subscription:
          type: string
          enum:
          - opt_in
          - opt_out
          description: '`opt_in` reaches everyone until they unsubscribe; `opt_out` reaches nobody until they explicitly subscribe. **Cannot be changed after creation** — flipping it would start mailing every contact who never asked, and nothing stored says which of them would have agreed.'
        description:
          type:
          - string
          - 'null'
          maxLength: 200
        visibility:
          type: string
          enum:
          - public
          - private
          default: private
          description: Whether the topic is listed on the hosted unsubscribe page to a contact who is not already opted in. A contact who explicitly opted in always sees it.
    Error:
      type: object
      description: Every non-2xx response from the API has this shape. `code` is stable and safe to branch on; `error` is a human sentence that may change.
      required:
      - error
      - code
      properties:
        error:
          type: string
          description: Human-readable explanation of the failure.
        code:
          type: string
          enum:
          - UNAUTHORIZED
          - FORBIDDEN
          - NOT_FOUND
          - VALIDATION_ERROR
          - RATE_LIMITED
          - MONTHLY_LIMIT_EXCEEDED
          - DAILY_LIMIT_EXCEEDED
          - PLAN_LIMIT_EXCEEDED
          - ALL_SUPPRESSED
          - RECIPIENT_DOMAIN_UNDELIVERABLE
          - DOMAIN_NOT_VERIFIED
          - SENDING_SUSPENDED
          - ACCOUNT_RESTRICTED
          - WORKSPACE_INACTIVE
          - SENDER_NOT_PERMITTED
          - SERVICE_PAUSED
          - LIST_SEND_HELD
          - BROADCAST_HELD
          - ATTACHMENT_STORAGE_ERROR
          - INTERNAL_ERROR
          - CONFLICT
          - BAD_REQUEST
          - PAYLOAD_TOO_LARGE
          description: Stable machine-readable error code.
        request_id:
          type: string
          description: Correlation id, returned on 500s and echoed in the `X-Request-Id` header on every response. Quote it in support requests.
    TopicSubscriptionResponse:
      type: object
      required:
      - topicId
      - contactId
      - subscribed
      properties:
        topicId:
          type: string
          format: uuid
        contactId:
          type: string
          format: uuid
        subscribed:
          type: boolean
    Topic:
      type: object
      required:
      - id
      - name
      - description
      - defaultSubscription
      - visibility
      - createdAt
      properties:
        id:
          type: string
          format: uuid
        name:
          type: string
        description:
          type:
          - string
          - 'null'
        defaultSubscription:
          type: string
          enum:
          - opt_in
          - opt_out
          description: What a contact who has never expressed a preference receives. Fixed at creation.
        visibility:
          type: string
          enum:
          - public
          - private
        subscriberCount:
          type: integer
          description: Contacts who explicitly opted in. Returned by create and list, not by get. For an `opt_out` topic this is the reachable audience; for an `opt_in` topic it is not, since everyone who never chose is subscribed too.
        createdAt:
          type: string
          format: date-time
        updatedAt:
          type:
          - string
          - 'null'
          format: date-time
    ListTopicsResponse:
      type: object
      required:
      - data
      properties:
        data:
          type: array
          items:
            $ref: '#/components/schemas/Topic'
    DeleteTopicResponse:
      type: object
      required:
      - id
      - deleted
      properties:
        id:
          type: string
          format: uuid
        deleted:
          type: boolean
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: 'An eusend API key, sent as `Authorization: Bearer eu_live_…`. Create one in the dashboard under API keys.'
externalDocs:
  description: eusend documentation
  url: https://eusend.dev/docs