Overview

In March 2024 Amazon refreshed the Fulfillment Inbound API (v2024‑03‑20) to expose preparation‑related fields for every merchant‑stock‑keeping unit (MSKU). The new endpoints let sellers programmatically read and write who is responsible for packaging, labeling, and the type of preparation required. This shift moves tasks that previously lived only in the Seller Central UI into API calls, giving high‑volume sellers a way to automate compliance, cut inbound mistakes, and accelerate shipment creation.

Key Points

• listPrepDetails operation — Returns every permissible preparation option for a specified MSKU, such as the allowed owners for packaging and labeling and the catalog of prep categories and types. Example: For SKU “XYZ‑789” the response may list prepOwner: ["Seller","Amazon"], labelOwner: ["Seller"], prepCategory: ["Polybag","BubbleWrap"].
• setPrepDetails operation — Accepts a chosen combination of prepOwner, labelOwner, prepCategory and prepUnit (e.g., “Standard”, “Fragile”) and writes those values into the inbound shipment plan. Example: Sending a JSON payload that sets prepOwner:"Seller" and prepCategory:"Polybag" updates the plan accordingly.
• Full API‑first compliance — Sellers can now embed preparation logic directly into inventory‑management or ERP systems, removing the need to open Seller Central for each product.
• Built‑in validation — The API cross‑checks the submitted owners and categories against the list returned by listPrepDetails, immediately rejecting unsupported combinations and preventing downstream rejections.
• Speed boost for large catalogs — Automating prep detail submission can shrink the time required to finalize inbound shipments by up to 30 % for sellers handling thousands of SKUs.

How the Updated Inbound API Works

1. Retrieve allowed preparation data — Issue a request for the target MSKU. The service replies with a JSON array that enumerates every valid , , , and . : For SKU “ABC‑123” the response includes , , , .