openapi: 3.0.3
info:
  title: Blend Public Borrowers & Parties Lenders & Assignments 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: Lenders & Assignments
  description: Lender users and application assignments.
paths:
  /lenders:
    get:
      operationId: listLenders
      tags:
      - Lenders & Assignments
      summary: List lenders
      description: Retrieve lender (employee) users available for assignment.
      parameters:
      - name: emails
        in: query
        schema:
          type: string
        description: Comma-separated lender emails to look up.
      responses:
        '200':
          description: A list of lenders.
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/Lender'
    post:
      operationId: createLenders
      tags:
      - Lenders & Assignments
      summary: Create lenders
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
      responses:
        '201':
          description: The created lenders.
    patch:
      operationId: updateLenders
      tags:
      - Lenders & Assignments
      summary: Update lenders
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
      responses:
        '200':
          description: The updated lenders.
    delete:
      operationId: removeLenders
      tags:
      - Lenders & Assignments
      summary: Remove lenders
      responses:
        '204':
          description: Removed.
  /applications/{id}/assignments:
    parameters:
    - $ref: '#/components/parameters/ApplicationId'
    get:
      operationId: listAssignments
      tags:
      - Lenders & Assignments
      summary: List assigned users
      responses:
        '200':
          description: The users assigned to the application.
    put:
      operationId: overrideAssignments
      tags:
      - Lenders & Assignments
      summary: Override assignees
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                assignees:
                  type: array
                  items:
                    type: object
                    properties:
                      userId:
                        type: string
                      role:
                        type: string
                        enum:
                        - PRIMARY_ASSIGNEE
                        - ASSIGNEE
      responses:
        '200':
          description: The updated assignments.
components:
  parameters:
    ApplicationId:
      name: id
      in: path
      required: true
      schema:
        type: string
      description: The application ID.
  schemas:
    Lender:
      type: object
      properties:
        id:
          type: string
        email:
          type: string
          format: email
        permittedSolutionSubTypes:
          type: array
          items:
            type: string
        roleNames:
          type: array
          items:
            type: string
  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.