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

# Create Upgrade Link

> Create a Stripe link the account owner opens in a browser to upgrade or manage their subscription. Nothing is charged by this call. Pass a plan to get a checkout link for that plan; existing subscribers may get an in-place plan change or a billing portal link instead. Omit plan to get a billing portal link for existing Stripe customers (returns 400 otherwise). Requires API key with billing:write permission.



## OpenAPI

````yaml /api-reference/openapi.json post /v1/billing/upgrade-link
openapi: 3.1.0
info:
  title: Migma.ai API (v1)
  description: >-
    API for managing brands, contacts, email generation, sending, and
    integrations.
  license:
    name: MIT
  version: 1.0.0
servers:
  - url: https://api.migma.ai
    description: Production
security:
  - apiKeyAuth: []
tags:
  - name: Projects/Brands
    description: Manage projects (brands) and import from websites
  - name: Contacts
    description: Manage your contacts, segments, tags, and topics
  - name: Segments
    description: Create and manage dynamic contact segments
  - name: Tags
    description: Organize contacts with tags
  - name: Topics
    description: Manage subscription topics and preferences
  - name: Emails
    description: Generate, send, and export emails
  - name: Email Validation
    description: Validate email content for compatibility and deliverability
  - name: Email Previews
    description: Preview emails across devices and email clients
  - name: Domains
    description: Manage sending domains and verification
  - name: Webhooks
    description: Manage webhook endpoints for real-time event notifications
  - name: Events
    description: Record customer events and conversions
  - name: Integrations
    description: Third-party platform integrations
  - name: Campaigns
    description: Create, schedule, send, and manage email campaigns
  - name: Billing
    description: View your plan and credits and create billing links
  - name: Project Editing
    description: Edit project assets, logos, images, and knowledge base entries
paths:
  /v1/billing/upgrade-link:
    post:
      tags:
        - Billing
      summary: Create Upgrade Link
      description: >-
        Create a Stripe link the account owner opens in a browser to upgrade or
        manage their subscription. Nothing is charged by this call. Pass a plan
        to get a checkout link for that plan; existing subscribers may get an
        in-place plan change or a billing portal link instead. Omit plan to get
        a billing portal link for existing Stripe customers (returns 400
        otherwise). Requires API key with billing:write permission.
      operationId: CreateUpgradeLink
      requestBody:
        required: false
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateUpgradeLinkRequest'
      responses:
        '200':
          description: Billing link created
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ApiResponseUpgradeLink'
              example:
                success: true
                data:
                  url: https://checkout.stripe.com/c/pay/cs_live_...
                  kind: checkout
                  sessionId: cs_live_...
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
components:
  schemas:
    CreateUpgradeLinkRequest:
      type: object
      properties:
        plan:
          type: string
          enum:
            - basic
            - premium
            - business
            - basic_annual
            - premium_annual
            - business_annual
          description: >-
            Target plan for a checkout link. Omit to get a billing portal link
            for existing Stripe customers.
    ApiResponseUpgradeLink:
      allOf:
        - $ref: '#/components/schemas/ApiResponse'
        - type: object
          properties:
            data:
              $ref: '#/components/schemas/UpgradeLink'
    ApiResponse:
      type: object
      properties:
        success:
          type: boolean
        data:
          nullable: true
        error:
          type: string
          nullable: true
      required:
        - success
    UpgradeLink:
      type: object
      properties:
        url:
          type: string
          description: >-
            Link the account owner opens in a browser to upgrade or manage the
            subscription
        kind:
          type: string
          enum:
            - checkout
            - portal
          description: Whether the link is a Stripe Checkout session or the billing portal
        sessionId:
          type: string
          description: Stripe Checkout session id, when kind is checkout
        orderId:
          type: string
          description: Migma order id associated with the checkout, when applicable
      required:
        - url
        - kind
    ApiError:
      type: object
      properties:
        success:
          type: boolean
          default: false
        error:
          type: string
        code:
          type: string
          description: >-
            Machine-readable error code (e.g., IDEMPOTENCY_CONFLICT,
            DOMAIN_CLAIMABLE).
        data:
          type: object
          description: >-
            Additional structured context for the error, such as the affected
            domain.
          additionalProperties: true
      required:
        - success
        - error
  responses:
    BadRequest:
      description: Bad request
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ApiError'
    Unauthorized:
      description: Unauthorized
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ApiError'
    Forbidden:
      description: Forbidden - Missing required permissions or access denied
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ApiError'
  securitySchemes:
    apiKeyAuth:
      type: apiKey
      in: header
      name: Authorization
      description: >-
        API key authentication. Use 'Authorization: Bearer YOUR_API_KEY' where
        YOUR_API_KEY is obtained from the Migma dashboard under Settings →
        Developers → API Keys.

````