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Synq tracks stock using an inventory ledger — a permanent, append-only record of every movement that has ever touched a SKU. Each time you receive new stock, write off shrinkage, or make a manual correction, Synq records the variant, location, quantity change, and the reason. The current on-hand quantity for any variant at any location is always derived from the sum of those recorded movements. This design gives you a complete, auditable history of your inventory without ever overwriting past data.

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How inventory adjustments work

When you post an adjustment, Synq permanently records a stock movement with the following fields:
  • variant_id — the product variant the movement applies to
  • location_id — the warehouse or fulfillment center where stock changed
  • quantity_delta — a signed integer: positive values add stock, negative values remove it
Each adjustment is written permanently and cannot be modified or deleted.
Inventory adjustments are permanent. Once a movement is recorded, it cannot be modified or deleted. To correct a mistake, post a new adjustment that reverses the error.

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Required headers

Every request to the Synq API requires three headers for tenant isolation and authentication.

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Adjust inventory

Use POST /api/v1/inventory/adjust to record any stock movement for a variant at a specific location. This single endpoint covers all use cases: receiving new goods, removing damaged units, correcting miscounts, and writing off shrinkage.

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Endpoint

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Request fields

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string (UUID)
required
The Synq variant UUID for the SKU whose stock you are adjusting.
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string (UUID)
required
The UUID of the warehouse or fulfillment location where stock is changing.
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integer
required
The signed quantity to apply. Use a positive integer to add stock (e.g. receiving a shipment), and a negative integer to remove stock (e.g. shrinkage or a manual write-off).
Use location_id to track stock independently per warehouse, retail store, or 3PL fulfillment centre. Synq computes available stock per variant_id + location_id pair, so you always know exactly how much stock is available at each site — not just globally.

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Examples

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Response

A successful adjustment returns 200 OK with the details of the recorded stock movement.
Response

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Response fields

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string (UUID)
The unique identifier of this recorded stock movement.
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string (UUID)
The organization this adjustment belongs to.
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string (UUID)
The tenant this adjustment belongs to.
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string (UUID)
The variant whose stock was adjusted.
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string (UUID)
The location where the stock movement occurred.
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string
The type of movement recorded. API-driven adjustments use "adjustment". Order fulfillment and returns use their own transaction types written automatically by the OMS.
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integer
The signed delta recorded for this movement. Positive means stock was added; negative means stock was removed.
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string | null
An optional reference identifier linking this movement to an external record (e.g. a purchase order number). null for generic API adjustments.
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number | null
Cost per unit at the time of the movement, if captured. null for generic API adjustments.
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string
Human-readable note attached to this movement. Defaults to "API Adjustment" for entries created via this endpoint.
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string (ISO 8601)
UTC timestamp of when this stock movement was recorded.

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Common use cases

Do not use this endpoint to reflect inventory consumed by order fulfillment. The Synq OMS automatically reserves and deducts inventory when it processes an order. Manually posting a negative delta on top of a fulfilled order will result in double-deduction.