> ## Documentation Index > Fetch the complete documentation index at: https://www.twicecommerce.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Update add-on > Updates an add-on of this catalog item. ## OpenAPI ````yaml https://server.twicecommerce.com/api/admin/openapi-mintlify.json patch /v1/admin/catalog/{id}/add-ons/{addonId} openapi: 3.0.2 info: title: TWICE Admin API description: "The TWICE Admin API is the merchant-facing API of the Twice platform. It is currently in alpha: endpoints and schemas may change without notice.\n\n## Webhooks\n\nWebhooks notify your systems when resources change in Twice. A webhook subscription pairs one event type with one HTTPS endpoint of yours; whenever a matching event occurs, we POST the event to that endpoint. Subscriptions and their delivery logs are managed in the Twice admin under **Account → Integrations**.\n\n### Event types\n\n- `order.created`\n- `order.deleted`\n- `order.updated`\n\n### Payload\n\nEvery delivery is an HTTP POST with a JSON body sharing a common envelope. The typed payload of each event type is documented in the **Webhooks** section of the sidebar.\n\n```json\n{\n\t\"eventId\": \"5f2eb3a6-6cbd-4a2e-9350-6e0d1e2f9a11\",\n\t\"eventType\": \"order.created\",\n\t\"eventTime\": \"2026-08-06T12:34:56.789Z\",\n\t\"resource\": \"order\",\n\t\"resourceId\": \"0d9e0a7c-3fd1-4c8f-9c0d-2b7c6f7f2a55\",\n\t\"apiVersion\": \"2025-06\",\n\t\"data\": { \"…\": \"the API representation of the resource, or null for deletes\" }\n}\n```\n\n`data` carries the resource in the same shape the REST API returns it, as of the API version in `apiVersion`. Each subscription is pinned to the API version that was the latest when the subscription was created, so a new API version never changes the payload shape you receive — moving to a newer version is an explicit update of the subscription.\n\n### Acknowledging deliveries\n\nRespond with any **2xx** status to acknowledge a delivery. Any other status — or a timeout — counts as a failed attempt. Respond as quickly as possible and do heavy processing asynchronously after acknowledging.\n\n### Delivery semantics\n\nDeliveries are **at-least-once**: the same event can occasionally be delivered more than once, so deduplicate on the `X-Twice-Event-Id` header (or the equal `eventId` body field). Ordering is not guaranteed — when it matters, use `eventTime` or re-fetch the current state of the resource via the API.\n\n### Retries\n\nFailed deliveries are retried up to 3 times (4 attempts in total) with growing backoff — roughly 10 s, 20 s, 40 s after the preceding attempt — giving up 10 minutes after the first attempt. After 3 consecutive events fail all their attempts, the subscription is automatically disabled (`disabledReason: TOO_MANY_FAILED_DELIVERY_ATTEMPTS`) and must be re-enabled manually in the admin. Individual deliveries can also be redelivered manually from the delivery log.\n\n### Verifying signatures\n\nEach subscription has a signing secret (prefixed `whsec_`), available in the admin. Deliveries carry an HMAC-SHA256 signature of the exact raw request body in the `X-Twice-Signature` header, formatted `sha256=`. Verify it against the raw body bytes — parse the JSON only after the signature checks out:\n\n```js\nimport { createHmac, timingSafeEqual } from 'node:crypto';\n\nconst expected = 'sha256=' + createHmac('sha256', secret).update(rawBody, 'utf8').digest('hex');\nconst signature = req.headers['x-twice-signature'];\nconst isValid =\n\ttypeof signature === 'string' &&\n\tsignature.length === expected.length &&\n\ttimingSafeEqual(Buffer.from(signature), Buffer.from(expected));\n```" version: 2025-06 servers: - url: https://server.twicecommerce.com security: - ApiKeyAuth: [] paths: /v1/admin/catalog/{id}/add-ons/{addonId}: patch: tags: - catalog summary: Update add-on description: Updates an add-on of this catalog item. operationId: admin.catalog.updateAddon parameters: - name: id in: path required: true schema: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ - name: addonId in: path required: true schema: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ requestBody: description: Body content: application/json: schema: type: object properties: defaultQuantity: default: 1 type: integer minimum: 1 maximum: 9007199254740991 quantityMode: default: selectable type: string enum: - selectable - fixed defaultVariantValueIds: default: [] maxItems: 50 type: array items: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ defaultSelected: default: false type: boolean required: default: false type: boolean orderIndex: default: 0 type: integer minimum: -9007199254740991 maximum: 9007199254740991 purchaseType: type: string enum: - booking - sales responses: '200': description: '200' content: application/json: schema: type: object properties: id: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ catalogItemId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ addonCatalogItemId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ defaultQuantity: default: 1 type: integer minimum: 1 maximum: 9007199254740991 quantityMode: default: selectable type: string enum: - selectable - fixed defaultVariantValueIds: default: [] type: array items: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ defaultSelected: default: false type: boolean required: default: false type: boolean orderIndex: default: 0 type: integer minimum: -9007199254740991 maximum: 9007199254740991 purchaseType: type: string enum: - booking - sales addonCatalogItem: type: object properties: id: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ name: type: string addonPricingMode: type: string enum: - standalone - percentage required: - id - name - addonPricingMode additionalProperties: false required: - id - catalogItemId - addonCatalogItemId - defaultQuantity - quantityMode - defaultVariantValueIds - defaultSelected - required - orderIndex - purchaseType - addonCatalogItem additionalProperties: false '400': description: '400' '401': description: '401' '403': description: '403' '404': description: '404' '429': description: '429' '500': description: '500' components: securitySchemes: ApiKeyAuth: type: apiKey name: X-API-KEY in: header description: API key for the Twice API ````