> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fuseai.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Presigned upload for a large import file

> Issues a presigned S3 PUT for a CSV/XLS/XLSX import file larger than the 10MB multipart line (up to 50MB). PUT the raw file bytes to `uploadUrl` with the same `Content-Type` you declared, within `expiresIn` seconds (600), then pass the returned `importId` to `POST /business/imports`. Nothing is parsed or billed at this step.

Errors:
- `422` `IMPORT_FILE_UNSUPPORTED` — The presign service refused the content type (reachable only if its allow-list and the documented enum drift apart).
- `422` `VALIDATION_FAILED` — filename missing/blank or contentType outside the three supported MIME types.
- `429` `RATE_LIMITED` — The lists rate bucket (120 requests/minute, 10,000/day per token owner) is exhausted.

Requires one of the following token scopes: lists.



## OpenAPI

````yaml /openapi.json post /business/imports/presign
openapi: 3.1.0
info:
  title: Fuse Business API
  version: 1.0.0
  description: >-
    External API for lists, campaigns, prospect search and contacts.
    Authenticate with your API token as HTTP Basic. All paths are under /api/v1.
servers:
  - url: https://api.tryfuse.ai/api/v1
    description: Production
security:
  - basicAuth: []
tags:
  - name: Lists
  - name: Custom columns
  - name: Smart columns
  - name: Exports
  - name: Campaigns
  - name: Knowledge hubs
  - name: Analytics
  - name: Website intent
  - name: Account
  - name: Prospect search
  - name: Campaign steps
  - name: Scheduled sends
  - name: Campaign templates
  - name: Agents
  - name: Research
  - name: Company search
  - name: Saved searches
  - name: Folders
  - name: Contacts
paths:
  /business/imports/presign:
    post:
      tags:
        - Lists
      summary: Presigned upload for a large import file
      description: >-
        Issues a presigned S3 PUT for a CSV/XLS/XLSX import file larger than the
        10MB multipart line (up to 50MB). PUT the raw file bytes to `uploadUrl`
        with the same `Content-Type` you declared, within `expiresIn` seconds
        (600), then pass the returned `importId` to `POST /business/imports`.
        Nothing is parsed or billed at this step.


        Errors:

        - `422` `IMPORT_FILE_UNSUPPORTED` — The presign service refused the
        content type (reachable only if its allow-list and the documented enum
        drift apart).

        - `422` `VALIDATION_FAILED` — filename missing/blank or contentType
        outside the three supported MIME types.

        - `429` `RATE_LIMITED` — The lists rate bucket (120 requests/minute,
        10,000/day per token owner) is exhausted.


        Requires one of the following token scopes: lists.
      operationId: createImportPresign
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                filename:
                  type: string
                  minLength: 1
                  maxLength: 500
                  description: >-
                    Original file name, e.g. leads.csv (1-500 characters). Free
                    text kept for your own reference: it does not name the
                    stored object, and the file's format is read from
                    contentType alone, so an extension that disagrees with
                    contentType changes nothing.
                contentType:
                  type: string
                  enum:
                    - text/csv
                    - application/vnd.ms-excel
                    - >-
                      application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
                  description: >-
                    MIME type of the file to upload: text/csv,
                    application/vnd.ms-excel (XLS) or
                    application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
                    (XLSX); the PUT to uploadUrl must send the same
                    Content-Type.
              required:
                - filename
                - contentType
      responses:
        '201':
          description: Success
          headers:
            RateLimit-Limit:
              schema:
                type: integer
              description: Requests permitted in the current window.
            RateLimit-Remaining:
              schema:
                type: integer
              description: Requests remaining in the current window.
            RateLimit-Reset:
              schema:
                type: integer
              description: Seconds until the current window resets.
          content:
            application/json:
              schema:
                type: object
                required:
                  - upload
                properties:
                  upload:
                    type: object
                    required:
                      - importId
                      - uploadUrl
                      - method
                      - expiresIn
                    properties:
                      importId:
                        type: string
                      uploadUrl:
                        type: string
                      method:
                        type: string
                        enum:
                          - PUT
                      expiresIn:
                        type: integer
              example:
                upload:
                  importId: >-
                    dXBsb2Fkcy82OGExZjIwYjljNDFkMjAwMTRiM2U5MDEvM2Y2ZjBlMmEtOGQ0Yi00ZTFhLTk3YzItNWQ4YjFmMGUyYTdjLmNzdg
                  uploadUrl: >-
                    https://fuseai-csv-uploads.s3.us-east-1.amazonaws.com/uploads/68a1f20b9c41d20014b3e901/3f6f0e2a-8d4b-4e1a-97c2-5d8b1f0e2a7c.csv?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Expires=600&X-Amz-Signature=9c1e4b2a7d3f5e6c
                  method: PUT
                  expiresIn: 600
        '400':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '402':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '403':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '404':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '409':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '422':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '429':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          description: Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      security:
        - basicAuth: []
components:
  schemas:
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            code:
              type: string
            message:
              type: string
            param:
              type:
                - string
                - 'null'
            doc_url:
              type:
                - string
                - 'null'
            request_id:
              type:
                - string
                - 'null'
          required:
            - code
            - message
      required:
        - error
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: >-
        Your API token (`af_…`) as the Basic-auth username, with an empty
        password.

````