Amazon & Marketplace Acronyms

MWSMarketplace Web Service

Amazon's legacy API for seller data access, now fully superseded by SP-API. MWS has been deprecated — sellers and integrators must migrate to SP-API. Any integration built on MWS should be treated as technical debt requiring migration.

Why MWS (Marketplace Web Service) matters in B2B integration

MWS (Marketplace Web Service) is part of the amazon & marketplace acronyms vocabulary that operators, IT leaders, and integration architects use when scoping ecommerce, ERP, EDI, and fulfillment projects. APIWORX integrates 200+ systems across this landscape — if MWS (Marketplace Web Service) touches your stack, we can help you connect it without custom code.

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ACOSAdvertising Cost of Sale

The ratio of Amazon ad spend to attributed ad revenue, expressed as a percentage. ACOS = Ad Spend ÷ Ad Revenue × 100. A lower ACOS indicates more efficient advertising. Target ACOS varies by margin profile and growth stage — profitability-focused sellers typically target below their gross margin percentage.

ASINAmazon Standard Identification Number

Amazon's unique 10-character alphanumeric identifier assigned to every product listed in its catalog. ASINs are the primary unit of catalog management on Amazon. A parent ASIN represents a product family; child ASINs represent individual variants (size, color). ASIN mapping is a critical step in any Amazon integration project.

BSRBest Seller Rank

A ranking assigned by Amazon to products within each category, updated hourly based on recent and historical sales velocity. A lower BSR number indicates higher sales volume. BSR is used as a proxy for demand and competitive position when evaluating product opportunities.

FBA Fees

The charges Amazon assesses on sellers using Fulfillment by Amazon, including fulfillment fees (per unit, based on size and weight), monthly storage fees (per cubic foot), and long-term storage fees (for inventory aged over 365 days). Accurate FBA fee modeling is required for profitability analysis on any Amazon SKU.

IPIInventory Performance Index

An Amazon score (0–1000) that measures how efficiently sellers manage their FBA inventory. A low IPI score (below 400) can result in storage capacity limits at Amazon fulfillment centers. Factors include excess inventory percentage, sell-through rate, stranded inventory, and in-stock rate.

LQSListing Quality Score

A metric used by various marketplace platforms (including Walmart) to measure the completeness and quality of a product listing — including title, description, bullet points, images, and attributes. Higher LQS correlates with better search visibility and conversion rates.