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

# Set master variant

> Promote this variant to be the master variant of its lander. If A/B testing is disabled, weights collapse to 100% on the new master.



## OpenAPI

````yaml https://backend-v2.landerlab.workers.dev/api/v2/openapi.json post /api/v2/workspaces/{workspaceId}/landers/{landerId}/variants/{variantId}/setMaster
openapi: 3.1.0
info:
  title: LanderLab API
  version: 2.0.0
  description: >-
    LanderLab public API. Authenticate with an API key using the X-API-Key
    header.
servers:
  - url: https://api.landerlab.dev
    description: Production
security: []
tags:
  - name: Account
    description: >-
      Discover the organization and workspaces your API key can access. Start
      here.
  - name: Workspaces
    description: List and manage workspaces.
  - name: Landers
    description: Create, update, publish and manage landers.
  - name: A/B Testing
    description: Manage variants and split-test weights.
  - name: Editor
    description: Load and save lander content and settings.
  - name: Analytics
    description: Query unified analytics across workspaces, landers and variants.
  - name: Leads
    description: Retrieve captured leads.
  - name: Integrations
    description: Manage account-level integrations.
  - name: Lander Integrations
    description: Attach and toggle integrations on landers.
  - name: Domains
    description: Manage custom domains.
  - name: Folders
    description: Organize landers into folders.
paths:
  /api/v2/workspaces/{workspaceId}/landers/{landerId}/variants/{variantId}/setMaster:
    post:
      tags:
        - A/B Testing
      summary: Set master variant
      description: >-
        Promote this variant to be the master variant of its lander. If A/B
        testing is disabled, weights collapse to 100% on the new master.
      responses:
        '200':
          description: Master variant updated
          content:
            application/json:
              schema:
                type: object
                properties:
                  message:
                    type: string
                required:
                  - message
                additionalProperties: false
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string
                required:
                  - error
                additionalProperties: false
        '403':
          description: Forbidden
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string
                required:
                  - error
                additionalProperties: false
        '404':
          description: Not Found
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: string
                required:
                  - error
                additionalProperties: false
      security:
        - ApiKeyAuth: []
components:
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: X-API-Key
      description: API key with ll_live_ prefix

````