eusend-dev System API

openapi: 3.2.0
info:
  title: eusend System 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: System
  description: Unauthenticated liveness and readiness checks.
paths:
  /health:
    get:
      operationId: getHealth
      summary: Liveness check
      description: Answers whether the API process is serving. Touches no dependency. No authentication.
      tags:
      - System
      security: []
      responses:
        '200':
          description: Serving.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HealthResponse'
  /health/ready:
    get:
      operationId: getReadiness
      summary: Readiness check
      description: Also proves Postgres and Valkey are reachable. Returns 503 when a dependency is down, so a plain status-code monitor is enough. No authentication.
      tags:
      - System
      security: []
      responses:
        '200':
          description: Every dependency reachable.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ReadyResponse'
        '429':
          description: Rate limited (`RATE_LIMITED`). 60 requests per minute per IP.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '503':
          description: A dependency is unreachable.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ReadyResponse'
components:
  schemas:
    ReadyResponse:
      type: object
      required:
      - status
      - checks
      - timestamp
      properties:
        status:
          type: string
          enum:
          - ok
          - degraded
        checks:
          type: object
          additionalProperties:
            type: string
          description: '`ok` per dependency, or the failure message.'
          properties:
            postgres:
              type: string
            valkey:
              type: string
        timestamp:
          type: string
          format: date-time
    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.
    HealthResponse:
      type: object
      required:
      - status
      - timestamp
      properties:
        status:
          type: string
          enum:
          - ok
        timestamp:
          type: string
          format: date-time
  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