3PL & Fulfillment
Should I fulfill Shopify orders with Amazon MCF, or keep FBA for Amazon and use a 3PL for my store?
Choosing between Amazon MCF and a dedicated 3PL to fulfill your Shopify orders.
Last updated September 16, 2026
Amazon Multi-Channel Fulfillment is a node that picks Shopify orders from FBA inventory. It is not a fulfillment strategy. Use it as overflow when the 3PL is dry, or as a second address on a handful of SKUs. Do not make Amazon the building that represents your brand.
Publish FBA available, not the ledger
FBA's picture of on-hand is a ledger, roughly daily, not a live pick face. Amazon Reserved is not sellable on Shopify. Unfulfillable FBA is not sellable either. If you publish the ledger balance, you will sell units Amazon will not ship today. Publish only FBA available minus Reserved minus an Amazon safety buffer. Treat in-transit-between-Amazon-warehouses the same way: it is not pickable. You inherit Amazon's file, including the one-day lag.
MCF splits and remaps shipping speeds
MCF will split. A line that Amazon can take and a line it cannot becomes two shipments, two tracking numbers, and two delivery dates. Shopify carrier rates do not map onto MCF. Amazon sells Standard, Expedited, and Priority, not your UPS Ground service. Remap checkout speed to those three before you turn the node on, or the customer bought a service you cannot buy back from Amazon. Decide per channel whether a split is allowed. Wholesale almost never is. MCF returns typically land back in FBA, not at your branded 3PL. Plan the reverse path before you route the outbound.
Keep branded pack and kits off Amazon
Branded pack, kits, and wholesale usually stay off Amazon. A kit Amazon will not assemble is a 3PL or in-house order. A retailer routing guide is not an MCF job. Keep FBA for Seller Central. Keep a 3PL or your own floor for the storefront, for inserts, and for anything that cannot look like Amazon. Route Shopify to MCF only when the preferred warehouse is short, and only for SKUs Amazon can actually pick.
The legacy connector cutoff
The legacy Shopify US Fulfillment app that talked to MCF sunsets 30 Sep 2026. Treat that as a cutoff for whatever connector you use today, not as a reason to pick a product. The replacement app can also offer Buy with Prime. That is a checkout badge, not a reason to make Amazon your only node. The decision does not change: one Amazon inventory pool serving both marketplace and DTC, or a protected FBA pile plus a separate 3PL. If you cannot name which SKUs may overflow to Amazon and which must never, you are not ready for MCF. You are ready for two oversells and a branded-pack complaint. MCF fees are Amazon's, not your 3PL rate card. Do not pick the node because a per-order number looked cheaper in a deck. Pick it because that SKU can live in FBA and still look like your brand when it has to.
Connect Claude or ChatGPT to your Fulfil data with the Fulfil MCP, then run this prompt on your own numbers.
You are the ops lead for a Shopify Plus brand that also sells on Amazon. Here is: sku, channel, on_hand_3pl, on_hand_fba, fba_reserved, fba_in_transit, is_kit, branded_pack (yes/no), wholesale (yes/no), preferred_warehouse, last_30d_shopify_orders, last_30d_mcf_orders, split_ok (yes/no). [paste] Produce: 1. Per SKU: FBA-only, 3PL-only, or MCF overflow, with a one-line why. 2. Publishable FBA qty (available minus Reserved minus a safety buffer). Flag rows that would oversell if the daily ledger were published as-is. 3. Orders that would split into two trackings if MCF is the fallback. 4. SKUs that must stay off Amazon (kits, branded pack, wholesale). MCF is a node, not a strategy. Mention 30 Sep 2026 only as the legacy US Fulfillment app cutoff.
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