Overview

Amazon’s Selling Partner API (SP‑API) now includes a JSON‑merge operation for the Listings Items v2021‑08‑01 endpoint and the JSON_LISTING_FEED feed. The change lets sellers and developers modify only the fields that need updating instead of sending an entire listing payload. This reduces request size, cuts validation failures, and speeds up catalog changes—critical for merchants handling large inventories or high‑volume automation.

Key Points

• Partial‑update capability — Sellers can send a patch that touches just the price or quantity field, avoiding the need to resend unchanged attributes.
• Standalone inventory edits — Quantity for a specific fulfillment node can be changed without including optional data such as restock dates or lead‑time values.
• B2B discount removal — Business sellers can delete a quantity‑discount plan from a Business‑to‑Business (B2B) offer without rebuilding the whole offer object.
• RFC 7396 compliance — The operation follows the JSON Merge Patch standard, meaning developers familiar with that spec can adopt it with minimal learning curve.
• Backward‑compatible rollout — Existing API calls continue to work; the new merge type is an additional option that does not break current integrations.
• Smaller payloads — A typical quantity‑only update drops from several kilobytes to a few hundred bytes, lowering bandwidth and processing time.

How the Merge Operation Works

1. Create a merge request — Build a JSON document that includes only the attribute(s) you want to change, such as "quantity": 42. For example, to raise the stock of SKU 12345 at the “US‑East” fulfillment node, the payload contains just that node’s quantity field.
2. Send to the Listings Items endpoint — Use the PATCH method with the new application/json-merge-patch content type. The API merges the supplied fields into the existing listing record, leaving all other attributes untouched.
3. — The response returns the updated listing snapshot, confirming that only the targeted fields were altered. If the request tries to modify a non‑existent attribute, the API returns a clear error without affecting other data.