Sync stock between Shopify, eBay and Amazon without changing your shipping software
If you sell the same products through a Shopify store, eBay and Amazon, TrueSKU can link your existing listings to one shared inventory record and update their stock quantities. You can keep buying labels through your existing services while maintaining stock in TrueSKU.
Who this suits, and who might prefer something else
This arrangement suits sellers who run their own Shopify store alongside eBay and Amazon listings of the same products, already have a routine for buying postage and dispatching orders, and want one stock figure that all three follow.
TrueSKU is not an order-management or dispatch system, and it does not replace Shopify. If you want one product that also handles picking lists, carrier labels and order routing, an all-in-one order-management system may suit you better. If you only sell through Shopify plus one marketplace and are happy managing everything inside Shopify with a marketplace app, you may not need a separate stock record.
What stays the same
Your stores, listings and dispatch routine carry on as they are:
- Your accounts. TrueSKU connects to your Shopify store, eBay account and Amazon seller account through their own APIs. It sits alongside them and does not replace them.
- Your existing listings. TrueSKU reads your products and variants as they are and, once a variant or listing is linked to a SKU, changes its stock quantity. It does not change titles, prices, images or descriptions, and you do not re-list anything.
- How you buy labels and dispatch. Use Shopify's shipping, eBay or Amazon label services, or any other label service you use for Shopify orders, exactly as you do now. TrueSKU reads each order from the channel itself, so it does not need to connect to your label tool.
What changes
There is some set-up work, and a change of habit afterwards:
- Linking variants and listings to SKUs, once. A Shopify variant or an eBay or Amazon listing is matched automatically where its SKU (or eBay custom label) matches a SKU in TrueSKU. The rest you link by hand, or in bulk by CSV.
- Checking starting stock. Enter a quantity for each SKU and compare it with what Shopify and your marketplaces currently show before sync is switched on.
- Recording stock in TrueSKU. Deliveries, returns and counts are recorded in TrueSKU rather than by editing a number in Shopify admin or on each marketplace. Once sync is on, TrueSKU's figure replaces the available quantity Shopify holds.
- Switching sync on deliberately. New stores start with stock sync off, and so does the account-wide switch. You enable one store at a time, and the account-wide switch last. Connecting a channel alone never changes a quantity.
Shopify specifics worth knowing
Shopify has a few details that differ from other channels:
- One location. TrueSKU manages the stock at one Shopify location. If your store has a single active location, TrueSKU uses it automatically. If you have several, you choose which one TrueSKU manages. Stock held at your other locations is not touched.
- Track quantity must be on. A variant whose "Track quantity" setting is off in Shopify has no stock to update, so TrueSKU skips it rather than guess.
- Variants are linked individually. Each Shopify variant links to its own SKU, so a product with sizes or colours needs a SKU per variant.
- Shopify updates itself at checkout. When a customer buys on your store, Shopify takes the unit off its own quantity as usual. TrueSKU then records the sale and updates eBay and Amazon.
A worked example
This is an illustration, not real data. You hold 10 units of one product, and have a Shopify variant, an eBay listing and an Amazon listing, all linked to the same SKU.
- TrueSKU holds 10 for the SKU, and all three listings show 10.
- A customer buys 2 on Shopify. Shopify shows 8 straight away. Once TrueSKU has picked up that order and applied it, the SKU has 8 available.
- TrueSKU then queues quantity updates, and the eBay and Amazon listings are set to 8 (and Shopify is confirmed at 8).
That is before any rules you have set. A buffer holds some stock back, a per-channel maximum caps what one channel shows, and a listing that sells a 2-pack with a multiplier of 2 would show 4 (8 divided by 2, rounded down).
Timing. By default TrueSKU checks each connected channel for new orders about every five minutes and sends changed quantities roughly every minute after that, and each marketplace takes its own time to process an update. Expect minutes rather than seconds: in the gap, eBay or Amazon can still show 10. Some sellers add a small buffer on their fastest-selling lines for that reason.
How sales reach TrueSKU from each channel
TrueSKU brings in sales from each channel directly. For each channel you switch on "direct sales collection" and choose where the first collection starts: the last 24 hours, from now, or a date you pick. That is the inbound half. Sending quantities back out to the listings is the outbound half, and the two are separate, as explained in inbound versus outbound sync.
- Shopify: TrueSKU reads new and changed orders from your store. An order cancelled on Shopify is flagged for review rather than silently reversed.
- eBay: TrueSKU reads your orders through eBay's APIs and matches them on eBay's unique order ID.
- Amazon: TrueSKU reads your merchant-fulfilled (FBM) orders through Amazon's Orders API. An order Amazon still shows as pending is held until Amazon confirms it. Amazon-fulfilled (FBA) orders are not imported, because Amazon manages that stock.
Avoiding double counting
Each order is recorded once, under its channel's own order number (per channel and seller). If the same order turns up again, for example in an overlapping check or a re-import, it is recognised and not applied a second time. A sale that cannot be applied safely, such as one on a variant that is not linked to a SKU, is held in the Sales Inbox instead of silently changing stock.
The safest set-up is one source of sales per channel. If you also send sales from another system (Packing Partner, CSV or the API), ask us first so the two sources agree on the order number and nothing is counted twice.
Limits and things to check
Check these before you switch sync on:
- Unlinked variants and listings. One with no SKU is not updated, and sales on it do not change stock. They wait in the Sales Inbox until you link it.
- Several Shopify locations. Choose the location TrueSKU should manage before enabling sync. Until a location is set, there is no stock to read or update.
- Untracked variants. Turn on "Track quantity" in Shopify for any variant you want TrueSKU to manage.
- Bundles and multipacks. A bundle SKU's availability follows its components (see how bundle availability is calculated). A multipack listing uses a multiplier.
- Amazon FBA and FBM. Only your own-fulfilled (merchant-fulfilled) quantities are updated. FBA stock is left to Amazon. There is an optional setting to let an FBA listing sell first.
- Other tools that write stock. An app that also sets inventory quantities on the same variants or listings will compete with TrueSKU. Once sync is on, TrueSKU treats its own figure as correct and sets the quantity back to it, so keep to one tool writing stock.
- Cancellations and changes. An order cancelled, or changed in quantity, after stock was applied is flagged for review rather than silently reversed.
- Timing. Updates take minutes and also depend on each channel's own API, so an outage or limit can delay them.
What it looks like in TrueSKU
Plans, trial and limits
Stock sync to your channels is included in the 21-day free trial, with no credit card required and a limit of 10,000 SKUs during the trial. After the trial, sending quantities to your channels needs a Channel Sync plan:
- Growth + Channel Sync: £69/month, up to 3,000 SKUs and 3 users.
- Pro + Channel Sync: £129/month, up to 10,000 SKUs and 10 users.
Packing Partner customers pay £58/month and £109/month respectively. The Starter, Growth and Pro plans without Channel Sync track stock but do not send it to your channels. Prices are in £ and no VAT is currently charged. Prices and limits can change, so check the pricing page for the current figures.
A short set-up checklist
- Start the free trial and connect Shopify, eBay and Amazon. Connecting only reads your listings.
- If your Shopify store has more than one location, choose the one TrueSKU should manage.
- Let the listings import, then link each variant and listing you sell to a SKU: automatically where codes match, by CSV, or by hand.
- Enter a starting quantity for each SKU and compare it with what each channel shows.
- Switch on direct sales collection for each channel, choosing where the first collection starts, so sales start reducing stock.
- Check the Sales Inbox for anything held, and resolve it.
- Switch on stock sync for one store, then the others, and the account-wide switch last.
- Watch the first updates on the Listings screen before leaving it to run.
More detail is in the help centre, and the stock sync overview has a short video and the common questions. You can also see which channels are supported on the integrations page. If you also sell through WooCommerce, see the WooCommerce, eBay and Amazon guide.
See TrueSKU with your own listings
21-day free trial, no card required.