Arthur Online Offers API

openapi: 3.2.0
info:
  title: Arthur Viewings Offers API
  version: 2.0.0
  description: Arthur Viewings API - the viewings surface of the Arthur API v2, the UK property management platform from Arthur Online (an Aareon company). Derived operation-for-operation from the provider's public Postman Documenter collection at https://developer.arthuronline.co.uk/. Every request is scoped to an Arthur entity via the mandatory X-EntityID header and authorised with an OAuth 2.0 Authorization Code access token.
  contact:
    name: Arthur Online API Support
    url: https://support.arthuronline.co.uk/
  termsOfService: https://www.arthuronline.co.uk/terms-and-conditions/
  x-derived-from: collections/arthur-online.postman_collection.json
  x-derived-by: API Evangelist enrichment pipeline
  x-derived-date: '2026-07-26'
servers:
- url: https://api.arthuronline.co.uk/v2
  description: Arthur API v2 production
security:
- arthurOAuth: []
tags:
- name: Offers
paths:
  /viewings/{viewing_id}/submit_offer:
    put:
      operationId: submitOfferOnViewing
      summary: Submit Offer on Viewing
      tags:
      - Offers
      parameters:
      - name: viewing_id
        in: path
        required: true
        description: Arthur viewing id.
        schema:
          type: integer
      - $ref: '#/components/parameters/EntityId'
      - $ref: '#/components/parameters/Strict'
      description: "This endpoint submits an offer to an existing viewing. Any fields that are not provided will not be changed. The API will return the updated data for the viewing in the response.\n\nSupported Fields \n The following fields are supported for the request body\n\nField \n Example \n Type \n Required? \n\namount \n 1200 \n String \n Yes \n\nfrequency \n Month \n String \n Yes (Week, Month, or Year)"
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                amount:
                  type: string
                  example: '1200'
                frequency:
                  type: string
                  example: Month
              required:
              - amount
            example:
              amount: '1200'
              frequency: Month
      responses:
        '200':
          description: The request was completed successfully without errors.
          content:
            application/json:
              schema:
                type: object
                properties:
                  status:
                    type: integer
                  data:
                    type: object
              example:
                status: 200
                data:
                  id: 633231
                  unit_id: 599238
                  unit_address: Unit 1 - Iron Bridge House, London, NW7 1JH
                  lat: 53.2457105
                  lng: -2.5220604
                  applicant:
                    id: 1182293
                    full_name: API Support
                  applicants:
                  - id: 1182293
                    full_name: API Support
                  viewing_status: Confirmed
                  viewing_date: '2023-02-27'
                  viewing_time: '10:53'
                  viewing_datetime: '2023-02-27T10:53:00'
                  offer_amount: '1200.00'
                  offer_frequency: Month
                  duration: 30
                  move_in_date: null
                  unit_available_from: null
                  unit_is_vacant: true
                  assigned_to:
                  - id: 100569
                    full_name: 'Max '
                  relationships:
                  - model: Unit
                    model_id: '599238'
                    ref: Unit 1 - Iron Bridge House
                  - model: Property
                    model_id: '280736'
                    ref: Iron Bridge House
                  tags: []
                  notes: []
                  source: ''
                  viewing_notes: ''
                  modified: '2023-03-06T10:53:14'
                  created: '2023-02-14T10:12:25'
                  deleted: false
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
components:
  responses:
    BadRequest:
      description: The request was invalid or malformed.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: The request was sent to a location that does not exist in the API.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: Missing, invalid or expired access token.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error: expired_token
            message: This token has expired.
  parameters:
    Strict:
      name: strict
      in: query
      required: false
      description: When true, abort the request instead of auto-creating an unknown Simple type. POST and PUT only.
      schema:
        type: boolean
    EntityId:
      name: X-EntityID
      in: header
      required: true
      description: The Arthur entity (account) the request is scoped to. Mandatory on every API call.
      schema:
        type: string
  schemas:
    Error:
      type: object
      description: Arthur error envelope.
      properties:
        status:
          type: integer
        error:
          type: string
          description: Machine-readable error code, e.g. expired_token.
        message:
          type: string
  securitySchemes:
    arthurOAuth:
      type: oauth2
      description: OAuth 2.0 Authorization Code flow. Access tokens are valid for 14 days; refresh tokens for 21 days. Register an application in Arthur Settings > OAuth Applications to obtain a client_id and client_secret.
      flows:
        authorizationCode:
          authorizationUrl: https://auth.arthuronline.co.uk/oauth/authorize
          tokenUrl: https://auth.arthuronline.co.uk/oauth/token
          refreshUrl: https://auth.arthuronline.co.uk/oauth/token
          scopes: {}