Amazon's MWS Shutdown: What Sellers Need to Know About Migrating to SP-API
Amazon retired its Marketplace Web Service (MWS) on March 31 2024, forcing all sellers to migrate to the Selling Partner API (SP‑API). SP‑API uses Login with Amazon and AWS Signature Version 4 and supports granular permission scopes such as orders, inventory, and reports.
Overview
Amazon has fully retired its legacy Marketplace Web Service (MWS) as of March 31 2024, forcing every seller and developer to switch to the newer Selling Partner API (SP‑API). The change eliminates the old endpoints that powered countless third‑party tools, and sellers who haven’t completed the migration risk losing critical automation. Understanding the migration path, the functional upgrades, and the immediate actions required is essential for keeping inventory, orders, and reporting workflows alive.
Key Points
- MWS shutdown date — All MWS endpoints stopped responding on March 31 2024, ending the API that many custom integrations still rely on.
- Phased deprecation — Amazon first limited specific MWS sections on October 31 2023, then removed the remaining services three months later.
- SP‑API mandatory — The Selling Partner API is now the sole supported method for programmatic access to seller accounts, covering everything from listings to fulfillment.
- Authentication overhaul — SP‑API uses Login with Amazon and AWS Signature Version 4, replacing the simple key‑pair model of MWS and tightening security.
- Granular permissions — Sellers can now grant applications access only to the data and actions they need, rather than the all‑or‑nothing access required by MWS.
- Third‑party alternatives — Amazon’s Seller Central App Store lists vetted solutions for inventory, pricing, analytics, and order management, offering a shortcut for sellers without in‑house development resources.
How the Migration Works
- Register as a developer — Log into Amazon Developer Central, create a developer profile, and obtain the required IAM credentials. Example: A seller who previously used a private MWS script signs up and receives an AWS Access Key and Secret Key.
- Create a new SP‑API application — Within Developer Central, generate a new SP‑API app, assign the necessary scopes (e.g., listings, orders, reports), and note the client ID and client secret.
Analysis & Recommendations
Why This Matters
MWS calls now return errors, so inventory syncs, order pulls, and report downloads can fail, disrupting sales. The new SP‑API security model and scoped permissions protect account data while enabling continued automation.
Key Takeaways
- MWS endpoints stopped responding on March 31 2024, ending the legacy API.
- SP‑API authentication requires Login with Amazon and AWS Signature Version 4, replacing the simple key‑pair model.
- Developers must register in Amazon Developer Central, create a new SP‑API app, and assign scopes like orders, inventory, and reports.
- Granular permissions let apps request only needed data, unlike MWS’s all‑or‑nothing access.
Recommended Actions
- →Log into Amazon Developer Central > Apps & Credentials, register as a developer and create a new SP‑API application with client ID/secret.
- →Map each MWS endpoint to its SP‑API equivalent using Amazon’s migration guide and update code to use AWS Signature V4 signing.
- →Run end‑to‑end tests in the SP‑API sandbox (sellingpartnerapi-na.amazon.com sandbox) before switching the production endpoint.
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