> ## Documentation Index > Fetch the complete documentation index at: https://documentation.qonversion.io/llms.txt > Use this file to discover all available pages before exploring further. # Set main offering > Atomically marks the offering as the project's main offering (`tag = 1`) and clears the previous main (`tag = 0`), inside a single transaction. No request body required — the action target is fully identified by the path parameter. Pass an `Idempotency-Key` header to make retries safe (the same key replays the original response). Experiment-variant offerings return `422` (typed code `cannot_setmain_experiment_variant`). ## OpenAPI ````yaml /api-reference/rest-api-v4.yaml post /offerings/{offering_id}/set-main openapi: 3.0.3 info: title: Qonversion REST API v4 version: '4.0' description: >- Qonversion REST API v4 follows REST standards. It has predictable resource-oriented URLs, accepts JSON-encoded request bodies, returns JSON-encoded responses, and uses standard HTTP response codes, authentication, and verbs. servers: - url: https://api.qonversion.io/v4 description: Production security: - secretAuth: [] tags: - name: Users description: Retrieve Qonversion users - name: User Properties description: Manage user-level attributes - name: Identities description: Link Qonversion users to your own auth IDs - name: Entitlements description: Entitlement definitions and user grants - name: Purchases description: A user's purchase history - name: Products description: Products configured in the Qonversion dashboard - name: Customers description: Aggregated customer records, properties, permissions, and metrics - name: Segments description: Dynamic and system segments of users - name: Experiments description: Paywall and offering A/B experiments - name: Screens description: No-code paywall screens — CRUD, publish, analytics - name: Analytics description: Charts, cards, cohorts, LTV, and insights - name: Exports description: Asynchronous data exports - name: Events description: Event catalog - name: Scheduled Reports description: Recurring reports delivered to external destinations - name: Integrations description: Third-party integrations configuration - name: Automations description: Event-driven automations - name: Project Settings description: Project-level configuration, secret, and store credentials paths: /offerings/{offering_id}/set-main: parameters: - name: offering_id in: path required: true schema: type: string maxLength: 64 pattern: ^[a-zA-Z0-9._:\- ]+$ example: premium_monthly post: tags: - Offerings summary: Set main offering description: | Atomically marks the offering as the project's main offering (`tag = 1`) and clears the previous main (`tag = 0`), inside a single transaction. No request body required — the action target is fully identified by the path parameter. Pass an `Idempotency-Key` header to make retries safe (the same key replays the original response). Experiment-variant offerings return `422` (typed code `cannot_setmain_experiment_variant`). operationId: v4SetMainOffering parameters: - name: Idempotency-Key in: header required: false schema: type: string responses: '200': description: Offering marked as main. content: application/json: schema: $ref: '#/components/schemas/V4Offering' example: object: offering id: winback url: /v4/offerings/winback tag: 1 product_ids: - premium_annual_2999 created_at: '2025-10-02T09:15:00Z' updated_at: '2025-11-14T08:45:00Z' '400': description: Invalid offering id. content: application/json: schema: $ref: '#/components/schemas/V4Error' '401': description: Missing or invalid authentication token. content: application/json: schema: $ref: '#/components/schemas/V4Error' '404': description: Offering not found in this project. content: application/json: schema: $ref: '#/components/schemas/V4Error' '409': description: Transactional conflict during set-main. content: application/json: schema: $ref: '#/components/schemas/V4Error' '422': description: >- Operation cannot be performed in the current state. Typed code: `cannot_setmain_experiment_variant` — the offering is owned by the experiments service. content: application/json: schema: $ref: '#/components/schemas/V4Error' '500': description: Internal error content: application/json: schema: $ref: '#/components/schemas/V4Error' security: - secretAuth: [] components: schemas: V4Offering: type: object required: - object - id - url - tag - product_ids - created_at - updated_at properties: object: type: string enum: - offering readOnly: true id: type: string maxLength: 64 pattern: ^[a-zA-Z0-9._:\- ]+$ example: premium_monthly url: type: string example: /v4/offerings/premium_monthly readOnly: true tag: type: integer format: int16 nullable: true description: | Offering role within the project. `1` = main offering (`TAG_MAIN`) — exactly one offering per project has tag=1 at any time; promote via `POST /v4/offerings/{offering_id}/set-main`. `0` = regular offering that was demoted from main. `null` = regular offering that has never been tagged. Treat `0` and `null` as equivalent on read. The Offerings endpoints filter out experiment-variant offerings, but legacy rows could carry historical values other than `0`, `1`, or `null`, so the response field is intentionally not enum-restricted. Write schemas restrict accepted values server-side. product_ids: type: array items: type: string maxLength: 255 pattern: ^[a-zA-Z0-9._:\- ]+$ description: Product UIDs that belong to this offering, in display order. created_at: type: string format: date-time example: '2025-09-15T12:30:00Z' readOnly: true updated_at: type: string format: date-time example: '2025-11-03T10:26:40Z' readOnly: true V4Error: type: object required: - error properties: error: type: object required: - type - code - message properties: type: type: string enum: - request - resource - logical - internal code: type: string description: | Machine-readable snake_case error code. Examples include `invalid_data`, `invalid_request`, `invalid_product_id`, `not_found`, `already_exists`, `offering_already_exists`, `product_not_in_project`, `cannot_set_main_directly`, `cannot_demote_main`, `cannot_patch_experiment_variant`, `cannot_delete_experiment_variant`, and `cannot_setmain_experiment_variant`. Resource-specific codes are documented on the corresponding reference page. message: type: string description: Human-readable description. May change; do not parse. details: type: array nullable: true description: Per-field validation errors, present on 400 validation failures. items: type: object properties: field: type: string message: type: string securitySchemes: secretAuth: type: http scheme: bearer bearerFormat: sk_… description: >- Bearer authentication using the project **Secret Key** (prefixed with `sk_`, or `test_sk_` for sandbox). All v4 public endpoints require the Secret Key — see [Authentication](/reference/v4/authentication). Never expose the Secret Key in client-side code. ````