Overview

Amazon's Merchant Fulfillment API enables third-party developers and sellers to integrate shipping functionality directly into their own applications and systems. The service terms that govern this API establish strict requirements around how developers build, maintain, and operate applications that connect to Amazon's shipping infrastructure. Understanding these terms is essential for any developer building seller tools or any seller evaluating third-party shipping solutions that leverage this API.

Key Points / What Sellers Need to Know

• API governance structure - The Merchant Fulfillment API service terms are a subset of the broader Amazon SP-API (Selling Partner API) Developer Agreement, but they contain specific provisions that apply exclusively to merchant fulfillment functionality.
• Application availability mandate - Any application that uses the Merchant Fulfillment API for commercial purposes must be available to end users 24 hours a day, 365 days a year, with no exceptions for downtime outside of what the terms permit.
• Speed requirements are strict - Developers must ensure that shipping rate and service information retrieved through the API is displayed to end users within 5 seconds at least 99.9% of the time each month.
• No extra fees allowed - Developers cannot charge sellers or other end users any additional fees for access to the Merchant Fulfillment API features, the information it provides, or any associated services.
• Rate integrity is non-negotiable - Shipping rates provided by Amazon through the API cannot be modified, replaced, obscured, or displayed differently than what Amazon provides.

How the Merchant Fulfillment API Works

The Merchant Fulfillment API is part of Amazon's Selling Partner API ecosystem and allows third-party applications to access shipping-related features that are natively available within Seller Central. Through this API, developers can build applications that let sellers purchase shipping labels, compare carrier rates, and manage fulfillment workflows without logging into Seller Central directly. The API provides programmatic access to Amazon's negotiated shipping rates from carriers like UPS, USPS, and FedEx, which sellers can then use to fulfill their merchant-fulfilled orders. This is particularly valuable for high-volume sellers and multi-channel businesses that need to streamline their shipping operations across platforms.