> ## Documentation Index > Fetch the complete documentation index at: https://docs.arcuserp.com/llms.txt > Use this file to discover all available pages before exploring further. # Transfer inventory between locations -- single or multi-item atomic > ATOMIC-CREATE (2026-05-12): accepts items[] for multi-line atomic transfers OR top-level product_id/quantity for single-item compat mode. All items transfer in one DB transaction; any failure rolls back all items (no partial writes). Inter-location transfer. Writes transfer_out + transfer_in ledger rows per item. Intra-entity: no GL. Intercompany: posts Due From / Due To GL entries. Field names: source_location_id (or from_location_id) and dest_location_id (or to_location_id) are accepted aliases. entity_from_id is injected from API key entity_id; do not supply in request body. ## OpenAPI ````yaml /openapi.yaml post /inventory/transfers openapi: 3.1.0 info: title: Arcus ERP Public API version: 1.0.0 description: > Arcus ERP public REST API. Designed for external integrations and data migration. **Authentication.** Bearer token (API key) via the `Authorization` header. Format: `Authorization: Bearer ark_live_ent__` (or `ark_test_*` for sandbox). API keys are issued per-entity in **Settings > Developers > API Keys**. **Entity scoping.** The entity is encoded in the API key prefix; routes are flat (e.g. `/v1/accounts`, `/v1/orders`, `/v1/products`). A small set of platform endpoints (migration, reconciliation, events, webhook endpoints, API keys) use the `/v1/entities/{entity_id}/...` form -- those are noted in their tags. **Key capabilities.** - Related-resource hydration via `?expand[]=` (see `x-arcus-expand` on each resource). - Cursor-based pagination (`starting_after` / `ending_before` / `limit`). - Idempotency via the `Idempotency-Key` header. - Webhook events for asynchronous notification. - Conditional requests / ETag for cache validation. servers: - url: https://api.arcuserp.com/v1 description: Arcus ERP API (accepts both live `ark_live_*` and test `ark_test_*` keys) - url: https://dev-api.arcuserp.com/v1 description: >- Dev sandbox API (test-only data, accepts `ark_test_*` keys against dev RDS) security: [] paths: /inventory/transfers: post: tags: - Inventory summary: Transfer inventory between locations -- single or multi-item atomic description: > ATOMIC-CREATE (2026-05-12): accepts items[] for multi-line atomic transfers OR top-level product_id/quantity for single-item compat mode. All items transfer in one DB transaction; any failure rolls back all items (no partial writes). Inter-location transfer. Writes transfer_out + transfer_in ledger rows per item. Intra-entity: no GL. Intercompany: posts Due From / Due To GL entries. Field names: source_location_id (or from_location_id) and dest_location_id (or to_location_id) are accepted aliases. entity_from_id is injected from API key entity_id; do not supply in request body. operationId: postInventoryTransfer parameters: - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: oneOf: - type: object description: Multi-item atomic mode required: - source_location_id - dest_location_id - items properties: source_location_id: type: string format: uuid description: 'Also accepted: from_location_id' dest_location_id: type: string format: uuid description: 'Also accepted: to_location_id' notes: type: string items: type: array minItems: 1 items: type: object required: - product_id - quantity properties: product_id: type: string format: uuid quantity: type: integer minimum: 1 notes: type: string - type: object description: Single-item compat mode required: - product_id - source_location_id - dest_location_id - quantity properties: product_id: type: string format: uuid source_location_id: type: string format: uuid description: 'Also accepted: from_location_id' dest_location_id: type: string format: uuid description: 'Also accepted: to_location_id' quantity: type: integer minimum: 1 notes: type: string examples: multi_item_transfer: summary: Multi-item inter-location transfer (atomic) description: > Transfer two SKUs from Warehouse A to Warehouse B in one atomic transaction. All items are inserted in one DB transaction -- any failure rolls back all. GL does NOT fire on draft create; it fires when the transfer is submitted. Field aliases: from_location_id / to_location_id also accepted. value: source_location_id: 91aa7588-4dc7-4edd-b172-7de91f5e1f78 dest_location_id: 828cabe6-3fa2-4fb7-a2af-2280bbaba335 notes: Weekly replenishment transfer to secondary warehouse items: - product_id: 7f6f3e14-eaad-4c45-b922-209f6dc6d140 quantity: 5 notes: Circuit Breaker 10A White - product_id: ec9288c3-12b1-474f-bb09-b0b15bb7a8ff quantity: 3 notes: Square D Breaker Black single_item_transfer: summary: Single-item transfer (compat mode) value: product_id: 7f6f3e14-eaad-4c45-b922-209f6dc6d140 source_location_id: 91aa7588-4dc7-4edd-b172-7de91f5e1f78 dest_location_id: 828cabe6-3fa2-4fb7-a2af-2280bbaba335 quantity: 10 notes: Emergency stock transfer responses: '201': description: | Transfer initiated (draft status; GL fires on submit). The `data.availability_warnings` array lists any line item whose requested quantity exceeds source-location availability at create time (warn-at-create, hard-block-at-ship; NetSuite/Acumatica transfer-order pattern). Draft creation is not blocked, but shipping a short line returns a 400 `insufficient_stock`. The array is empty when every item has enough on hand at the source. content: application/json: schema: type: object properties: object: type: string enum: - inventory_transfer_result data: type: object properties: availability_warnings: type: array description: >- Per-item source-availability shortfalls at create time (empty when none). items: type: object properties: transfer_item_id: type: string format: uuid product_id: type: string format: uuid requested_qty: type: integer available_qty: type: integer shortfall: type: integer examples: transfer_result: summary: Transfer created in draft status value: data: id: e1ce42dc-e9ae-40c4-a923-aa93100b0947 entity_from_id: 65dcd234-53c3-4f54-b772-ee349528d497 entity_to_id: 65dcd234-53c3-4f54-b772-ee349528d497 location_from_id: 91aa7588-4dc7-4edd-b172-7de91f5e1f78 location_to_id: 828cabe6-3fa2-4fb7-a2af-2280bbaba335 transfer_number: SB-TRF-0000001 status: draft transfer_type: internal notes: Weekly replenishment transfer to secondary warehouse gl_posted: false availability_warnings: [] items: - id: d8c6bb7a-9c4c-446a-8518-d6f9398dbedc transfer_id: e1ce42dc-e9ae-40c4-a923-aa93100b0947 product_id: 7f6f3e14-eaad-4c45-b922-209f6dc6d140 quantity_sent: '5.0000' quantity_received: '0.0000' notes: Circuit Breaker 10A White '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' security: - ApiKeyAuth: [] components: parameters: IdempotencyKey: name: Idempotency-Key in: header required: false description: | Client-generated unique key for idempotent POST/PATCH/DELETE operations. Alias for the Idempotency parameter. Max 255 chars. On retry with the same key, the original response is returned without re-executing the operation. Keys expire after 24 hours. schema: type: string maxLength: 255 responses: Error: description: Error response (400/401/403/404/409/422/429/500) content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' schemas: ErrorEnvelope: type: object description: | Canonical error response envelope. All API errors use this shape. required: - error - code properties: error: type: string description: Machine-readable error key example: not_found code: type: string description: Machine-readable error code (often same as error) example: not_found type: type: string enum: - validation_error - permission_error - not_found - conflict - rate_limit - internal - expand_error - not_implemented example: not_found hint: type: string description: Human-readable one-sentence explanation (English) example: >- The requested order does not exist or does not belong to this entity. param: type: string description: The parameter that caused the error, if applicable example: expand[0] required: type: string description: The scope required (only on insufficient_scope errors) example: accounts:read request_id: type: string description: >- Unique request ID for support tracing (maps to CloudWatch log stream) example: req_abc123 securitySchemes: ApiKeyAuth: type: http scheme: bearer description: | API key issued per entity via Settings > Developers > API Keys. Each key carries scopes (e.g. orders:read, products:write). Bearer token format: Authorization: Bearer ark_live_ent__ Test keys use ark_test_ent__. Both are issued per entity via Settings > Developers > API Keys. ````