Multi-Store Stock Sync for WooCommerce — shared stock across several stores

Multi-Store Stock Sync for WooCommerce is for anyone selling the same goods on two or more WooCommerce sites: a retail and a wholesale domain, stores in different languages, a second brand, a separate site for a marketplace. The warehouse is one, so the stock has to be one too. Without sync, a manager copies numbers between admin panels by hand, and a customer pays for an item that is already gone.

The plugin makes one site the master: its stock is the truth. Every other site is a satellite that follows the master by SKU. A sale, a cancellation, a restocked refund or a manual edit on any site shows on all the others within seconds.

What the customer sees

The customer sees correct availability on every site of the network, and nothing else. The last two pairs sold on the wholesale site: a few seconds later the retail site shows “Out of stock”. An order is cancelled: the items are back on every site.

• Checkout stays fast. Nothing is sent during checkout: the change goes into a queue and is delivered in the background right after the request.
• Variations too. Size and colour sync separately, and so do products whose stock is kept on the parent.
• Products without stock tracking get the stock status: “Out of stock” on the master means the same on the satellites.

What the store admin gets

A WooCommerce → Multi-Store Sync page with four tabs: connections, sync log, SKU report, settings. The plugin interface is available in English, Ukrainian and Russian.

• Connected in a minute. On the master: “Add satellite”, copy the key. On the satellite: paste the key and “Connect”. Right after connecting, the satellite compares catalogues and takes the master’s stock for every matching SKU.
• Status of every site: last successful answer, last error, how many changes wait in the queue. Buttons: “Check connection”, “Push all stock”, “Pause”, “Delete”.
• The log shows what went where and how it ended: sale −2 from order #1078, stock now 19. Filters by level, site and SKU; you choose the retention (30 days by default).
• The SKU report lists products that exist on one side only. Usually that is a typo in a SKU that would otherwise take weeks to find.

Pro: prices, reviews, reconciliation, alerts

• Prices per site role. For each satellite: the price source (the master regular price or a separate price list such as “Wholesale”), a factor (1.2 = +20%, 0.9 = −10%, or an exchange rate) and the number of decimals. A price list is a field in the product and variation card on the master.
• Sales. Either the satellite receives the master’s sale prices with dates or it keeps its own sales, your choice per site. If a new price from the master is not above the satellite’s own sale price, it is not applied, and both logs say why, so a sale never disappears silently.
• Limits: prices only for chosen categories, and any product can be left out with the “Do not send the price” tick in its card.
• Reviews travel between every site by SKU: with rating and the “verified owner” mark, without the author’s e-mail or IP, without duplicates or echoes. The average rating is recalculated.
• Hourly reconciliation fixes any drift left by failures on its own, no button needed.
• An e-mail when a site of the network stops answering, and another one when it is back.

How it works, step by step

1. Something changes on a satellite: a sale, a cancellation, a restocked refund or a manual edit. The plugin records it as an exact change (−2, +1) with a unique event id.
2. Right after the request, a background worker sends the change to the master in a signed message.
3. The master applies the change with WooCommerce’s atomic stock update. Delivering the same event again changes nothing: it is counted exactly once.
4. The master sends the resulting number to every satellite with a version. An older version never overwrites a newer one.
5. Values that came from the network are never sent back, so two sites cannot ping-pong the same change.
6. If the master is down, changes wait in the queue and retry with a pause from 30 seconds up to an hour. The satellite meanwhile shows “master stock plus its own unsent changes”.

Under the hood

• Changes, not numbers. A satellite sends the master a change with a unique event id, not “there are 17 here now”. Two simultaneous sales on different sites never overwrite each other.
• Exactly once. The event id is stored on the master; the same event retried after a network error returns “already counted” instead of taking the item twice.
• Versioned values. Every number from the master carries the time it was read; a satellite drops an outdated value even when it arrives later.
• Security. Every message is signed with HMAC-SHA256 and carries a timestamp and a one-time nonce; a foreign signature, an old message or a replay is refused. Secrets are encrypted in the database. The connection key is shown only in the admin, to users who manage WooCommerce.
• Nothing extra leaves the stores. Only SKUs, stock and stock statuses travel between the sites (plus prices and reviews without e-mails in Pro). No customer data is sent anywhere, and CatCode receives nothing.
• A burst of sales is one message. The master marks the SKU as changed and reads the stock at sending time, so ten sales in a row make one update, in batches of up to 100 SKUs.
• Cleans up after itself. Deleting the plugin removes its tables, options and cron events; product stock stays as it is.

Installation

1. On every site of the network: Plugins → Add New → Upload Plugin, choose catcode-multistore-sync-for-woocommerce-1.0.1.zip (Pro) or the free build, and activate it.
2. On the site whose stock is correct today, open WooCommerce → Multi-Store Sync → Settings and choose the “Master (warehouse)” role.
3. On the Connections tab, enter a satellite name, click “Add satellite” and copy its connection key.
4. On the other site, choose the “Satellite” role, paste the key and click “Connect”. The satellite compares catalogues and takes the master’s stock.
5. Check the SKU report: it lists products whose SKU did not match.
6. For Pro: on the master, paste the licence key from the e-mail after payment or start the 7-day trial. Satellites get Pro from the master automatically.