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

# Mint signed upload URLs

> Request one signed upload URL per file, then PUT each file's bytes to its `signed_url`. Files are workbook-level — not mapped to templates.



## OpenAPI

````yaml /api-reference/openapi.json post /migrations/{migration_id}/files
openapi: 3.1.0
info:
  title: Vern Migration API
  version: 1.0.0
  description: >-
    Run Vern as a headless migration engine. Create a migration, upload a
    customer's files, run the managed agent to generate a preview, then execute
    and export clean data. See the Migration API guides for concepts and
    walkthroughs.
servers:
  - url: https://app.vern.so/api/v1
security:
  - apiKey: []
tags:
  - name: Catalog
    description: Discover the sources and templates you set up in the Vern UI.
  - name: Migrations
    description: Create a migration workspace and upload a customer's files.
  - name: Runs
    description: 'Drive the managed agent: generate, refine, execute, answer, and observe.'
  - name: Export
    description: Download a migration's validated data as CSV.
paths:
  /migrations/{migration_id}/files:
    parameters:
      - $ref: '#/components/parameters/MigrationId'
    post:
      tags:
        - Migrations
      summary: Mint signed upload URLs
      description: >-
        Request one signed upload URL per file, then PUT each file's bytes to
        its `signed_url`. Files are workbook-level — not mapped to templates.
      operationId: createUploads
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - files
              properties:
                files:
                  type: array
                  minItems: 1
                  items:
                    type: object
                    required:
                      - name
                    properties:
                      name:
                        type: string
                      content_type:
                        type: string
            example:
              files:
                - name: contacts.csv
                  content_type: text/csv
      responses:
        '201':
          description: One signed upload per requested file.
          content:
            application/json:
              schema:
                type: object
                properties:
                  files:
                    type: array
                    items:
                      $ref: '#/components/schemas/SignedUpload'
              example:
                files:
                  - name: contacts.csv
                    storage_path: workbooks/b3d9.../<uuid>-contacts.csv
                    signed_url: https://storage.vern.so/object/upload/sign/...&token=...
                    token: ey...
                    content_type: text/csv
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '429':
          $ref: '#/components/responses/RateLimited'
components:
  parameters:
    MigrationId:
      name: migration_id
      in: path
      required: true
      description: The migration ID returned by Create a migration.
      schema:
        type: string
        format: uuid
      example: c0a8012e-4f1b-4d3a-9b2c-7e6f5a4b3c2d
  schemas:
    SignedUpload:
      type: object
      properties:
        name:
          type: string
        storage_path:
          type: string
        signed_url:
          type: string
          description: PUT the file's bytes here.
        token:
          type: string
        content_type:
          type: string
    Error:
      type: object
      properties:
        error:
          type: string
          description: A human-readable error message.
      required:
        - error
  responses:
    BadRequest:
      description: Malformed request.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: API key missing, malformed, or revoked.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: The referenced resource isn't in your account.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    RateLimited:
      description: Rate limit hit — back off and retry.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error: Too many requests
  securitySchemes:
    apiKey:
      type: apiKey
      in: header
      name: x-api-key
      description: Your Vern API key. Create one at Settings → API keys.

````