> ## Documentation Index > Fetch the complete documentation index at: https://docs.joinluminous.com/llms.txt > Use this file to discover all available pages before exploring further. # Buy a shipping label for a fulfillment order > Buy a shipping label for the given fulfillment order, register the shipment in Luminous, and return the base64 label bytes plus tracking. This operation is idempotent per fulfillment order — retries return the already-purchased label instead of buying postage twice. Success bodies are wrapped in a top-level "data" key; errors return { "error": "" }. Optionally route the label to a printer: pass print_station_id (a Luminous print station from GET /pickflow/print-stations) to enqueue the purchased label into that station's print queue. The response then carries print_job_id. ## OpenAPI ````yaml /api-reference/build.yaml post /pickflow/fulfillment-orders/{fulfillmentOrderId}/label openapi: 3.0.0 info: title: Luminous API version: 1.0.0 description: API documentation for Luminous servers: - url: https://{companyName}.api.joinluminous.com/external/api/v1 variables: companyName: default: companyName description: Your company-specific subdomain security: [] tags: - name: Products description: Get and manage products - name: Pricing description: Manage price schedules, levels, and customizations - name: BOMs description: Manage Bills of Materials (BOMs) - name: Labels description: Label rendering via Labelary ZPL service - name: Companies description: Manage business accounts and their associated data - name: Contacts description: Manage contact information for individuals - name: Suppliers description: Manage suppliers (factories) — vendors used on purchase orders - name: Supplier SKUs description: Manage per-supplier SKU and unit-cost overrides for products - name: Locations description: Manage warehouses and locations - name: Inventory description: Get and adjust product stock levels - name: Lots description: Create, update, and delete product lots (batches) - name: Transfer Orders description: Manage transfer orders - name: Fulfillment Orders description: Manage fulfillment orders and picklists - name: Purchase Orders description: Get and modify purchase orders - name: Receiving Reports description: Manage receiving reports - name: Payment Obligations description: Manage payment obligations for purchase orders - name: Sales Orders description: Manage sales orders and sales order shipments - name: Purgatory description: >- Inspect and resolve non-posted sales orders in the purgatory staging workflow - name: PickFlow Shipping description: >- Provider-agnostic shipping rates, services, packages, and label purchase for PickFlow - name: Cycle Counts description: >- Create, drive, and post PickFlow cycle counts — batches, per-warehouse sessions, and CSV import/export - name: Print Stations description: List paired print stations and enqueue print jobs to them - name: Invoices description: Get and manage invoices - name: Work Orders description: >- Manage work orders — production lifecycle, steps, materials, links, shipments, and comments - name: Production Batches description: Group and manage work orders as production batches - name: Bills description: >- Accounts payable bill management, payments, attachments, allocations, and variance - name: Prepayments description: Manage vendor prepayments and applications - name: Vendor Credits description: Manage vendor credits and applications - name: Vendor Returns description: Manage vendor returns and credit generation - name: Customer Returns description: Manage customer returns (sales returns), receiving, and restock behavior - name: Stock Snapshot description: Point-in-time stock snapshots with export support - name: Consumption description: Consumption reports and exports - name: Inventory Aging description: Cost-layer-based inventory aging reports - name: Bills Reports description: Accounts payable bills aging reports - name: Forecast description: Materialized forecast data - name: Reports description: Close the books, inventory discrepancy, transaction COGS, and EDI reports - name: Tags description: Add/remove tags across various resources - name: Custom Fields description: Get and set custom fields across various resources - name: Currency description: Currency configuration, exchange rates, and conversion - name: Integration Mappings description: Manage integration mappings for external systems - name: Integration Field Mappings description: Manage field-level mappings between Luminous and external systems paths: /pickflow/fulfillment-orders/{fulfillmentOrderId}/label: post: tags: - PickFlow Shipping summary: Buy a shipping label for a fulfillment order description: >- Buy a shipping label for the given fulfillment order, register the shipment in Luminous, and return the base64 label bytes plus tracking. This operation is idempotent per fulfillment order — retries return the already-purchased label instead of buying postage twice. Success bodies are wrapped in a top-level "data" key; errors return { "error": "" }. Optionally route the label to a printer: pass print_station_id (a Luminous print station from GET /pickflow/print-stations) to enqueue the purchased label into that station's print queue. The response then carries print_job_id. operationId: buyPickflowFulfillmentOrderLabel parameters: - in: path name: fulfillmentOrderId required: true description: The fulfillment order to buy a label for. schema: type: integer requestBody: required: true content: application/json: schema: type: object required: - carrier_code - service_code - weight properties: carrier_code: type: string description: Carrier code to ship with. service_code: type: string description: Shipping service code to use. package_code: type: string nullable: true description: Package type code. confirmation: type: string nullable: true description: Delivery confirmation option. ship_date: type: string format: date nullable: true description: Date the shipment will be tendered to the carrier. weight: type: object required: - value properties: value: type: number minimum: 0.01 description: Package weight value. units: type: string nullable: true description: Weight units (e.g. ounces, pounds). dimensions: type: object nullable: true properties: length: type: number width: type: number height: type: number units: type: string ship_to: type: object nullable: true description: Optional override of the ship-to address. properties: name: type: string street1: type: string postal_code: type: string label_format: type: string nullable: true enum: - pdf - png - zpl - PDF - PNG - ZPL description: Format of the returned label. test_label: type: boolean nullable: true description: When true, request a test (non-billable) label. print_station_id: type: string format: uuid nullable: true description: >- Optional print routing. ID of a Luminous print station (from GET /pickflow/print-stations) to enqueue the purchased label into that station's print queue. Enqueue failures are non-fatal — the label is always returned. packing_session_id: type: string nullable: true description: >- Optional packing session identifier to associate with the print job. responses: '200': description: Label purchased (or already-purchased label returned) content: application/json: schema: type: object properties: data: type: object additionalProperties: true description: Base64 label bytes and tracking details. properties: print_job_id: type: string nullable: true description: >- ID of the print job enqueued to the requested print station. Null when print_station_id was not sent or the enqueue failed (non-fatal — the label is still returned). '401': description: Unauthorized content: application/json: schema: type: object properties: error: type: string '404': description: Fulfillment order not found content: application/json: schema: type: object properties: error: type: string '422': description: Validation error content: application/json: schema: type: object properties: error: type: string security: - BearerAuth: [] components: securitySchemes: BearerAuth: type: http scheme: bearer description: >- Authenticate using a bearer token. To create a token, navigate to /settings/api-tokens and click Create API Token. ````