Milan Inventory Sync for WooCommerce

Yes, and completely. Every feature this plugin contains is enabled: two-way Shopify sync, price and listing sync, order import and status sync, reserved stock, all four conflict strategies, the full analytics screen with CSV export, unlimited channels and unlimited history. Nothing is time-limited, quota-limited or waiting for a licence key. The separately distributed add-on is not an unlock. It contains adapter code for other marketplaces, plus features whose implementations are not in this plugin at all.

WooCommerce, by default. Milan is designed around Woo-as-canonical. You can override this per channel, and per event type within a channel, in the conflict settings.

Three mechanisms. Optimistic locking. Every stock write is a compare-and-swap against a version number. Two sales landing in the same second on two marketplaces cannot both write "2 units left" — the second one loses the swap and re-reads. Without this, one of them silently overwrites the other, and the store tells the world it has one more unit than it does. This is in the free plugin. Fast sync. A sale on any channel reduces WooCommerce stock, which Milan pushes to every other channel within seconds. Reserved stock buffers (Pro). Hold N units back per channel, so the race happens on units 3 and 4 rather than on units 1 and 0.

No, and it is worth knowing which before you set expectations. Shopify does, and Milan uses them — orders and stock changes arrive in seconds. Amazon, eBay, Etsy, and Walmart do not, in a form a WordPress site can use. Amazon's notifications go to AWS SQS or EventBridge rather than to an HTTP endpoint; eBay's require verifying a rotating ECDSA signature; Etsy and Walmart do not offer partner webhooks at all. Milan polls those, on a schedule you control. This reflects what those marketplaces currently offer partner integrations. Milan polls them instead, which is slower than a webhook but does not miss changes.

This plugin has no tiers. It is one plugin and all of it works. The separately distributed add-on is sold in three, differing by which marketplace adapters they include, how many sites the licence covers, and what support comes with it: Personal adds Amazon, eBay, Etsy and Walmart plus alerting; Business covers three sites; Agency covers twenty-five and adds the regional marketplaces, multi-warehouse routing and white-labelling.

Yes for Pro's Amazon integration. Amazon SP-API requires you to be a registered Amazon seller in good standing. Milan handles the OAuth and API connection, but Amazon's own requirements apply.

eBay Trading API just needs a Developer account (free) and your eBay seller account credentials.

Yes. Variable products map to channel-specific variant structures (Amazon parent/child ASINs, eBay variations, Etsy inventory items, Shopify variants).

Milan fails safe. If Amazon's API is unreachable, Woo keeps running normally. Sync attempts queue with exponential backoff. Once the channel is back, queued jobs process. Alerts (Pro) notify you of extended outages.

When Woo and a channel disagree — Woo shows 5 units, Amazon shows 3 because somebody bought there — Milan applies a strategy: WooCommerce wins, the channel wins, the most recent change wins, or hold it for manual review. Free always uses "WooCommerce wins", which is the safe default. Personal Pro lets you choose per channel. Business Pro lets you choose per channel and per event type — "WooCommerce wins on stock, eBay wins on price" — and adds the manual-review queue and bulk resolution. Every conflict is recorded either way, including the ones Milan settles automatically in a microsecond, with the strategy that settled it. The question a merchant eventually asks is not "is my stock right" but "why did my stock change", and that record is the answer.

Yes, on the Agency tier — and those five are marked beta. They are built against each marketplace's published documentation and tested against recorded responses, but they have not been validated against a live seller account in each region. Sync a handful of products and check before you point one at a catalogue. The Channels screen says the same thing.

Yes. Milan is HPOS-native. Marketplace orders arrive as first-class Woo orders under HPOS.

You can build a channel adapter. The ChannelAdapterInterface documented at milan.bytloop.com/docs/channel-adapter-guide is a standard extension point. Third-party channels welcome.

Free support in the wp.org support forum. Pro customers get email support at support@bytloop.com with 24h SLA. Agency includes video call support for setup and troubleshooting.

The hooks reference lives at milan.bytloop.com/docs/hooks and in /docs/hooks.md in the plugin.