Crosslist from Shopify to Amazon — one stock pool, two very different storefronts

On this page

• Why this route is easier than most, and where the work actually is
• Barcodes, Brand Registry and the GTIN exemption
• Shopify variants against Amazon parent and child ASINs
• One stock pool: Shopify locations, FBM and FBA
• Price parity and Amazon’s fair pricing policy
• Referral fee against payment processing
• Marketplace Connect, Buy with Prime, and what FLUF does instead
• What transfers, field by field
• What syncs, and the direction that does not
• Returns, and who owns the customer
• Setting it up, step by step
• What it costs
• Sources and verification
• Related guides

Why this route is easier than most, and where the work actually is

A Shopify brand selling new stock is the seller Amazon was built to onboard. The two obstacles that stall a typical marketplace seller, no product identifier and a category that refuses used goods, mostly do not apply to you. Your products are new, and Shopify has been quietly collecting the identifier all along: the Barcode field on every variant, which Shopify sets per variant alongside price, SKU and inventory.

So the question is not “can this go to Amazon?” but “what shape does it take there, and what happens to one warehouse once two storefronts sell from it?” That is a different conversation from the one an eBay reseller needs, and one framing runs through all of it: Shopify is a storefront you own, Amazon is a catalogue you contribute to. On Amazon a product page belongs to the catalogue, and what you add is an offer against it, unless you hold the brand and register it.

Barcodes, Brand Registry and the GTIN exemption

Amazon needs an existing ASIN or an accepted product identifier such as an EAN, UPC or ISBN. Review each Shopify variant’s barcode before crosslisting. Use legitimate GS1-registered identifiers that match your brand, and do not use internal warehouse codes as barcodes.

What you get for that barcode depends on whether the product already exists in Amazon’s catalogue.

If it exists (a wholesaler’s product, or your brand already listed by a retailer), your barcode matches an ASIN and you become one more offer on that page. The title, images and bullets are the catalogue’s.

If it does not exist, your barcode creates a new catalogue entry, and this is where Brand Registry matters. Amazon’s UK Brand Registry eligibility asks for an active registered or pending trademark from the trademark office of a country with an Amazon store, as a word mark or a design mark containing words, and for the brand name to be permanently on the product or its packaging. Enrolment has no fee, and it gives you control of the listing content, protection against other sellers editing it, A+ content and a brand store. For a DTC brand that has invested in photography and copy, it is the difference between Amazon showing your work and showing whatever a third party uploaded first.

The GTIN exemption is for the stock you never barcoded: a limited run, a bundle, a product you make yourself. Amazon’s GTIN guide describes the route: in the listing workflow you choose “I don’t have a product ID”, and if an “Apply now” button appears you submit a product name and images showing every side of the product and its packaging. FLUF Connect does not use the exemption: a product with no ASIN and no valid barcode is refused before an attempt is spent. List an exempt item on Amazon yourself, add its ASIN to the product in FLUF, and the sync covers it from then on.

Shopify variants against Amazon parent and child ASINs

A Shopify product is one page with up to three options and 2,048 variants, each variant carrying its own barcode, SKU, price and stock. Amazon models the same thing as a family: a parent listing that is not itself buyable, child listings that are, and a variation theme (Size, Color, SizeColor, and so on) that is fixed per category and must be the same on every child.

The models look alike and differ in three ways.

Review Amazon’s allowed variation choices. Shopify options may not all be supported by the Amazon category. Confirm the category, sizes, colours and other required details, and complete any missing attributes highlighted by FLUF.

The family is built on Amazon’s side. FLUF Connect treats each Shopify variant as its own product record and pushes it to Amazon as its own SKU. Where those SKUs attach to existing child ASINs, Amazon’s family already groups them. Where they create new catalogue entries, they arrive standalone; the parent and the variation relationship are set up in Seller Central, a one-off task per product line.

The SKU is the key, not the listing id. Every Amazon listing call is addressed by seller id and SKU. FLUF Connect uses your Shopify SKU as that key and stores the ASIN separately as the public identity, so keep Shopify SKUs unique per variant and never reuse one.

One stock pool: Shopify locations, FBM and FBA

Whether stock is one pool depends on who holds it. Shopify tracks inventory per location, and you tell FLUF Connect which location to read and adjust. Amazon’s two fulfilment modes behave differently against that location.

Merchant-fulfilled (FBM). You hold the stock and ship each order. FLUF supports this mode and updates Amazon quantities after Shopify sales. Turn off Shopify’s “continue selling when out of stock” setting for these variants to avoid accepting orders beyond available stock.

Fulfilled by Amazon (FBA). You ship cartons to an Amazon fulfilment centre and Amazon holds, picks and ships. Those units are not in your Shopify location, and the offer’s quantity is whatever Amazon counts on its shelves. FBA stock is not in your Shopify count and no listing sync can put it there, because the two numbers describe different piles of goods. FLUF Connect recognises an FBA offer by the absence of a merchant-declared quantity, treats it as live rather than sold out, and never tries to set it.

If you want FBA units to appear in Shopify, that is a different product: Amazon’s Multichannel Fulfilment app for Shopify syncs Amazon-held inventory into Shopify as available stock and routes Shopify orders to Amazon’s warehouses. It lists nothing on Amazon. The two tools solve opposite halves of the problem and can coexist, provided FBA-held SKUs are not also counted at your own location.

Price parity and Amazon’s fair pricing policy

You can price differently on the two channels, and most brands do, because the fee structures differ. What you cannot do is let the Amazon price drift above what a buyer can find elsewhere. Amazon’s Marketplace Fair Pricing Policy lists, among practices that harm customer trust, “setting a price on a product or service that is significantly higher than recent prices offered on or off Amazon”, and says the response can be removing the Buy Box, removing the offer, or in serious or repeated cases suspending the account. The same document flags excessive shipping fees, judged against public carrier rates.

“Off Amazon” includes your own Shopify store. The scenario to watch is a Shopify promotion: you cut a product to £29 for the weekend, the Amazon offer stays at £45, and the gap is visible to a system built to compare them. Either keep Amazon at or under Shopify at all times and absorb the referral fee in margin, or run promotions on both at once. FLUF Connect helps with the second: a price edit on the product record is pushed to the Amazon offer. Review the actual selling price on both channels when running a promotion.

Referral fee against payment processing

Put like against like: each platform has a monthly subscription and a per-sale charge, and the per-sale charges are of a different order.

Amazon’s per-sale charge is the referral fee, a percentage of the total sale price including postage. On Amazon UK the Clothing and Accessories rate is tiered: 5% up to £15, 10% between £15 and £20, and 15% above £20, with a £0.25 minimum per item; Home Products are 8% up to £20 and 15% above; Beauty, Health and Personal Care 8% up to £10 and 15% above; Consumer Electronics 7%; Footwear, Sports, Toys and most other categories 15%. The apparel, home and beauty tiers are January 2026 revisions. The Professional plan is £25 a month excluding VAT; Individual is £0.75 an item without API access, so a tool like FLUF Connect needs Professional. On Amazon US the shape is the same with different numbers: Clothing 17% above $20, a $0.30 minimum, and $39.99 a month for Professional.

Shopify’s per-sale charge is card processing. On Shopify UK the Basic plan is £25 a month billed monthly (£19 on annual billing), Grow £65 (£49), Advanced £344 (£259); online card rates are 2% + 25p, 1.7% + 25p and 1.5% + 25p respectively, and a store that uses a third-party payment provider instead of Shopify Payments pays an additional 2%, 1% or 0.6%.

The last two rows are the point. Amazon’s referral fee buys the visit, which on Shopify you buy separately through advertising, so whether 15% is dear depends on what a Shopify visit costs you. A brand with strong organic traffic will find Amazon expensive; one whose Shopify sales are mostly paid will find 15% cheap against its blended acquisition cost.

Marketplace Connect, Buy with Prime, and what FLUF does instead

Three things get called “the Amazon app”, and they do different jobs.

Shopify Marketplace Connect is Shopify’s own channel app. Shopify’s help centre says it connects a store to Amazon, eBay and two United States-only marketplaces, syncs product and order changes from the store outwards, and converts prices into each marketplace’s currency. Its fee is not on Shopify’s help pages; Shopify staff on the community forum describe it as 50 marketplace-synced orders a month included, then 1% of synced orders, capped at $99 a month.

Buy with Prime and the Multichannel Fulfilment app are the reverse direction. They put a Prime checkout on your Shopify store and let Amazon’s warehouses ship your Shopify orders; Amazon’s guide says you need not sell on Amazon.com at all to use them, and that the app requires a Professional Seller Central or MCF account, stock in Amazon fulfilment centres and Shopify Payments. They list nothing on Amazon.

FLUF Connect lets you use Shopify as your source catalogue and Amazon as one of 51 destinations. Connect Amazon from the dashboard; no browser extension is needed.

One caveat. Amazon went live in FLUF Connect on 5 September 2026, and the first sellers are still exercising the new-listing attribute maps, the part of Amazon’s documentation that is least reliable. Offer-only listings against existing ASINs are the safer path today; new creates may need a second attempt once the missing attributes are named.

What transfers, field by field

What syncs, and the direction that does not

Shopify supports two-way inventory and order sync in FLUF Connect. Amazon sale protection currently works in one direction only.

Amazon sales do not yet update Shopify stock automatically. Reconcile Amazon sales in Shopify yourself. Keep an inventory buffer on Amazon if you need to reduce the risk of overselling during busy periods.

Returns, and who owns the customer

On Shopify the buyer is yours: the email, the order history, the consent, the returns policy. On Amazon the buyer is Amazon’s. FLUF Connect does not read Amazon buyer names or addresses at all, because Amazon classes them as restricted data needing a separate approval; your FLUF orders panel shows the order and the SKU, and the address lives in Seller Central.

Amazon.co.uk’s returns policy gives buyers 30 days from delivery for most items, and for seller-fulfilled orders the seller provides a prepaid return label and pays the return postage. A brand used to setting its own window and charging for returns should price Amazon orders assuming returns are free to the buyer and prompt. The pattern most brands settle on is Amazon for discovery and the first purchase, Shopify for the relationship, which only works if the two channels are honest with each other about stock and price.

Setting it up, step by step

1. Check the Shopify side. Every variant you intend to sell on Amazon needs a barcode in Shopify’s Barcode field and a unique SKU. Fix them in Shopify so they are right everywhere.
2. Be on Amazon’s Professional plan and, if you own the brand, enrol in Brand Registry first.
3. Connect Shopify to FLUF Connect and choose the inventory location FLUF should read and adjust. Your catalogue imports with barcodes, SKUs, prices and stock.
4. Connect Amazon. Approve access on Amazon’s consent page and select your selling region: North America, Europe or Far East.
5. Map categories. Your Shopify product types are matched to Amazon product types once; edit any FLUF got wrong, and the edit sticks for future creates.
6. Crosslist in a small batch first. Offer-only matches should go live; new creates may come back naming missing attributes, which you add in Shopify and retry.
7. Build parent–child families in Seller Central for any new catalogue entries, then push the rest.
8. Set your Amazon price rule so promotions on Shopify never leave Amazon higher, and keep a buffer on Amazon quantity until Amazon sale detection is live.

What it costs

7 days for £1, then from £9/month, then plans from £9/month. Starter includes unlimited listings, crosslisting, inventory sync, order sync and bulk operations, which is everything this page describes. Relisting, offer management and smart pricing come with the plans above Starter. Separately you need Amazon’s Professional plan (£25 a month ex VAT in the UK, $39.99 in the US), since Individual has no API access, and your existing Shopify plan; card rates and referral fees are charged by those platforms exactly as they would be without FLUF.

Sources and verification

Every fee, limit and policy here was checked against a primary source on 8 September 2026.

• Amazon UK selling plans and referral fees — plan fees, the tiered Clothing, Home and Beauty rates effective 5 January 2026, flat category rates and the £0.25 minimum.
• Amazon US selling plans and referral fees — US plan fees and category rates, and the plan comparison listing apps and APIs under Professional only.
• Shopify UK pricing — plan prices, card rates and third-party payment fees.
• Amazon UK Brand Registry — eligibility and what enrolment provides.
• Amazon’s GTIN guide — the “I don’t have a product ID” exemption route and what the application needs.
• Amazon on variation listings — parent, child and variation theme definitions.
• Shopify Help Center on variants — variant and option limits, per-variant fields.
• Amazon Marketplace Fair Pricing Policy (PDF) — the “on or off Amazon” clause and the enforcement ladder.
• Shopify Marketplace Connect — supported marketplaces, sync direction and currency conversion; and Shopify staff on its fee.
• Amazon’s MCF and Buy with Prime app guide — inventory direction and account requirements.
• Amazon.co.uk returns policies — the 30-day window and seller-provided prepaid labels for seller-fulfilled orders.

Check current Marketplace Connect pricing and Amazon fulfilment fees before choosing your setup. Review new Amazon listings and their required attributes before publishing.

Related guides

• Sell on Shopify — the complete seller guide
• Sell on Amazon — the complete seller guide
• Amazon vs Shopify — a catalogue against a storefront
• Crosslist from eBay to Amazon
• Crosslist from Shopify to eBay
• Sell on eBay — the complete seller guide
• All marketplace guides
• All crosslisting routes
• Crosslist from Wix to Amazon