bunq Handshake API

openapi: 3.2.0
info:
  title: bunq Public Handshake API
  description: Grounded, representative subset of the bunq Public API.
  version: v1
  contact:
    name: bunq API documentation
    url: https://doc.bunq.com
  license:
    name: bunq API Terms of Service
    url: https://doc.bunq.com
servers:
- url: https://api.bunq.com/v1
  description: Production
- url: https://public-api.sandbox.bunq.com/v1
  description: Sandbox
security:
- sessionToken: []
tags:
- name: Handshake
  description: Installation, device registration, and session bootstrap. Establishes the RSA-signed API context.
paths:
  /installation:
    post:
      operationId: createInstallation
      tags:
      - Handshake
      summary: Register a client public key (create Installation)
      description: First handshake step. POST the PEM-encoded 2048-bit RSA public key of your locally generated key pair. The response returns an installation `Token` and the bunq `server_public_key`. The Token authenticates the following device-server and session-server calls; the server public key is used to verify server response signatures. This call is not signed.
      security: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InstallationInput'
      responses:
        '200':
          description: Installation created; installation Token and server public key returned.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Response'
        '400':
          $ref: '#/components/responses/Error'
  /device-server:
    post:
      operationId: createDeviceServer
      tags:
      - Handshake
      summary: Register the device (create DeviceServer)
      description: Second handshake step. Registers your API key and (optionally) a list of permitted IPs against the installation. Send the installation Token in `X-Bunq-Client-Authentication` and sign the request body with your private key in `X-Bunq-Client-Signature`.
      security:
      - installationToken: []
      parameters:
      - $ref: '#/components/parameters/ClientSignature'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/DeviceServerInput'
      responses:
        '200':
          description: DeviceServer registered.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Response'
        '400':
          $ref: '#/components/responses/Error'
  /session-server:
    post:
      operationId: createSessionServer
      tags:
      - Handshake
      summary: Open a session (create SessionServer)
      description: Third handshake step. Opens a session and returns the session `Token` used in `X-Bunq-Client-Authentication` for all subsequent business calls, plus the user object(s) and the session timeout. Send the installation Token in `X-Bunq-Client-Authentication` and sign the body with your private key.
      security:
      - installationToken: []
      parameters:
      - $ref: '#/components/parameters/ClientSignature'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SessionServerInput'
      responses:
        '200':
          description: Session opened; session Token and user returned.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Response'
        '400':
          $ref: '#/components/responses/Error'
components:
  schemas:
    Response:
      type: object
      description: Generic bunq response envelope. Every bunq response wraps its payload in a top-level `Response` array whose items are single-key objects keyed by the resource type (for example `Payment`, `MonetaryAccount`, `Id`, `Token`). Modeled generically here; see doc.bunq.com for the exact per-resource shape.
      properties:
        Response:
          type: array
          items:
            type: object
            additionalProperties: true
    SessionServerInput:
      type: object
      required:
      - secret
      properties:
        secret:
          type: string
          description: Your bunq API key (the same secret registered on the device-server).
    ErrorResponse:
      type: object
      description: bunq error envelope.
      properties:
        Error:
          type: array
          items:
            type: object
            properties:
              error_description:
                type: string
              error_description_translated:
                type: string
    DeviceServerInput:
      type: object
      required:
      - description
      - secret
      properties:
        description:
          type: string
          description: Human-readable device description.
        secret:
          type: string
          description: Your bunq API key.
        permitted_ips:
          type: array
          description: Optional list of IPs permitted to use this device. Use ["*"] to allow any IP (wildcard) where enabled.
          items:
            type: string
    InstallationInput:
      type: object
      required:
      - client_public_key
      properties:
        client_public_key:
          type: string
          description: PEM-encoded 2048-bit RSA public key (PKCS#8) of your client key pair.
  responses:
    Error:
      description: A bunq error response envelope.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
  parameters:
    ClientSignature:
      name: X-Bunq-Client-Signature
      in: header
      required: true
      description: Base64-encoded RSA (PKCS#1 v1.5, SHA-256) signature of the request body, produced with your private key. Required on the handshake calls and, historically, on all authenticated requests. The server signs its response in X-Bunq-Server-Signature, verifiable with the installation server_public_key.
      schema:
        type: string
  securitySchemes:
    sessionToken:
      type: apiKey
      in: header
      name: X-Bunq-Client-Authentication
      description: Session token obtained from POST /session-server, sent on every business call. In addition, each request body must be signed with your private key and the signature sent in the X-Bunq-Client-Signature header (see the ClientSignature parameter). bunq is not a simple bearer-token API.
    installationToken:
      type: apiKey
      in: header
      name: X-Bunq-Client-Authentication
      description: Installation token from POST /installation, used only for the device-server and session-server handshake calls.