openapi: 3.0.3
info:
  title: Blend Public Borrowers & Parties Home Lending Applications API
  description: 'The Blend Public API is the documented REST surface of the Blend Labs digital lending and account-opening platform (developers.blend.com). It lets lenders and certified technology partners programmatically create and manage lending applications across home lending (mortgage), consumer lending, and deposit account opening; manage borrowers/parties, documents and disclosures, pricing, closings and eSignature packages, follow-ups (tasks), lenders and assignments; subscribe to webhook event notifications; and export industry-standard loan files (Fannie Mae 3.2, MISMO 3.3.1/3.4) into a loan origination system (LOS).


    endpointsModeled: The paths, methods, and resource names in this document are modeled from Blend''s public developer documentation and reference at developers.blend.com (llms.txt endpoint index, Quick Start Guide, LOS Guide, and the create/export home-loan guides). Blend does not publish a fully open self-service OpenAPI - the reference is credential-gated and access tokens are issued to Blend customers and certified partners. Request/response schemas below are representative rather than field-complete; obtain the authoritative machine spec at https://developers.blend.com/blend/openapi once you hold API credentials.'
  version: 12.0.0
  contact:
    name: Blend Labs
    url: https://developers.blend.com/blend
  termsOfService: https://blend.com/legal/terms-of-service/
servers:
- url: https://api.blendlabs.com
  description: Production
- url: https://api.beta.blendlabs.com
  description: Beta / integration environment (used in Blend's documentation examples)
security:
- bearerAuth: []
tags:
- name: Home Lending Applications
  description: Create and manage mortgage (home lending) applications.
paths:
  /home-lending/applications:
    get:
      operationId: listHomeLendingApplications
      tags:
      - Home Lending Applications
      summary: List home lending applications
      description: Lists home lending applications. Supports filters used for export flows such as exportable=true and losId-exists=false.
      parameters:
      - name: exportable
        in: query
        schema:
          type: boolean
        description: Return only applications ready to export.
      - name: losId-exists
        in: query
        schema:
          type: boolean
        description: Filter by whether an LOS ID has been assigned.
      responses:
        '200':
          description: A list of home lending applications.
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/Application'
        '401':
          $ref: '#/components/responses/Unauthorized'
    post:
      operationId: createHomeLendingApplication
      tags:
      - Home Lending Applications
      summary: Create a home lending application
      description: Creates a new home lending application. The minimum required input is the primary borrower party's name (firstName, lastName) and email.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateApplicationRequest'
      responses:
        '201':
          description: The created application.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Application'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
  /home-lending/applications/{id}:
    parameters:
    - $ref: '#/components/parameters/ApplicationId'
    get:
      operationId: getApplication
      tags:
      - Home Lending Applications
      summary: Get application data
      responses:
        '200':
          description: The application.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Application'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      operationId: patchApplication
      tags:
      - Home Lending Applications
      summary: Update application data
      description: Update application metadata, including the losId, or archive the application.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                losId:
                  type: string
                archived:
                  type: boolean
      responses:
        '200':
          description: The updated application.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Application'
        '404':
          $ref: '#/components/responses/NotFound'
    delete:
      operationId: deleteApplication
      tags:
      - Home Lending Applications
      summary: Delete an application
      responses:
        '204':
          description: Deleted.
        '404':
          $ref: '#/components/responses/NotFound'
components:
  responses:
    NotFound:
      description: The requested resource was not found.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: Authentication failed or the token is not authorized for this tenant.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    BadRequest:
      description: The request was invalid.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  schemas:
    Application:
      type: object
      properties:
        id:
          type: string
        solutionSubType:
          type: string
        loanPurposeType:
          type: string
        losId:
          type: string
        parties:
          type: array
          items:
            $ref: '#/components/schemas/Party'
    Party:
      type: object
      properties:
        id:
          type: string
        name:
          type: object
          properties:
            firstName:
              type: string
            lastName:
              type: string
        email:
          type: string
          format: email
        econsent:
          type: string
    CreateApplicationRequest:
      type: object
      required:
      - party
      properties:
        party:
          type: object
          required:
          - name
          - email
          properties:
            name:
              type: object
              properties:
                firstName:
                  type: string
                lastName:
                  type: string
            email:
              type: string
              format: email
        loanPurposeType:
          type: string
          enum:
          - PURCHASE
          - REFINANCE
        applicationExperienceType:
          type: string
          example: FULL_APPLICATION
        applicationSource:
          type: object
          properties:
            type:
              type: string
            name:
              type: string
        crmId:
          type: string
        losId:
          type: string
        leadId:
          type: string
        referenceNumber:
          type: string
        sendEmailInvite:
          type: boolean
    Error:
      type: object
      properties:
        error:
          type: string
        message:
          type: string
  parameters:
    ApplicationId:
      name: id
      in: path
      required: true
      schema:
        type: string
      description: The application ID.
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: Blend authenticates requests with an authorization Bearer token. Each call must also send blend-api-version (to pin the API version) and blend-target-instance (tenant~instance) headers. API Secret Keys are exchanged for short-lived, request-scoped JWTs at Blend's API Gateway. Credentials are issued to Blend customers and certified partners - contact your Blend account team or partnerships to obtain them.