Guides

Trunk vs StockUnison, from one side of the fence

Both keep products that share a SKU in sync. Trunk does it across a dozen channels beyond Shopify, with bundling; StockUnison does it inside Shopify, from $9 a month against $35.

Updated 2 November 2026

This comparison is written by one of its subjects, so read it accordingly. What makes it checkable anyway is that nearly every difference is structural — which places each app reaches, what relationship it models between products, what each is priced on — and you can verify all of it against both public listings in ten minutes. Where a judgement appears, it is labelled.

The short answer

These two do the same core job at very different reach. Both keep products that carry one SKU showing one count, so selling any of them lowers the rest. Trunk does that across a dozen sales channels beyond Shopify and adds bundling; StockUnison does it inside Shopify only — in one store or across several of your own — free to 50 SKUs, then from $9 a month against $35.

• Choose Trunk if anything you sell lives outside Shopify — Amazon, eBay, Etsy, TikTok, Walmart, Square POS, WooCommerce — or if bundles must draw down their components.
• Choose Trunk if a track record is a requirement: 408 reviews at 4.9, and the lowest complaint share in the category.
• Choose StockUnison if every product is in Shopify and the same item is sold as several products, or your own stores sell from one shelf: one shared count per SKU, priced by SKUs kept in sync and never by orders.
• Choose StockUnison if you want to see every change before anything is written — every connection starts in preview mode, every write is logged, and it never creates or deletes products — or you want one main store’s counts copied one way into the others, which Trunk does not model.

Which one fits is almost entirely decided by whether anything you sell lives outside Shopify.

The job they actually share

Trunk calls it syncing duplicate listings. StockUnison calls it shared stock. It is the same idea: the SKU identifies a physical item, every product carrying that SKU — or, on a marketplace, every listing — is a way of selling the same shelf, and they should therefore hold one number between them.

This matters more than the multi-store framing most of this category uses, because the commonest version of the problem has nothing to do with multiple stores — one mug sold on its own and in three bundles, a product duplicated for a campaign, the same jacket under two names. Both apps handle that. Most store-to-store sync tools cannot touch it.

Choose Trunk when

• Anything sells outside Shopify. Amazon, eBay, Etsy, Faire, TikTok, Walmart, Square POS, BigCommerce, Squarespace, Wix, WooCommerce, Bandcamp. This is the whole reason Trunk exists, and StockUnison reaches none of them.
• Bundles and kits must draw down their components. A genuinely hard problem, well solved there, and outside what StockUnison models.
• You want QuickBooks or Xero in the loop.
• A track record is a requirement. 408 reviews, 4.9 average, a 1.2% complaint share — the best record in the category we measure, and it has held that position across three readings since July. StockUnison has none. With inventory, refusing to extend trust to a new tool is a defensible position, and this row alone settles it for some people.

Choose StockUnison when

• Every product is in Shopify — one store or several — and you are paying Trunk for twelve channels you do not use.
• You want the whole thing previewed first. Nothing is written until you have seen every SKU it found on more than one product and the counts each product currently holds, at any catalogue size, on the free plan, for as long as you like.
• You want it to stop rather than guess. If the numbers stop adding up — a CSV import, another app writing stock — StockUnison stops updating that SKU and says why, instead of spreading a count it cannot explain. Ambiguous SKUs are reported and never synced.
• You also need one store feeding others, one way. StockUnison’s other shape is a main store whose counts connected stores copy and can never write back to — a supplier-to-reseller or retail-to-B2B arrangement that a channel tool does not model at all.
• The order volume is high. StockUnison prices by SKUs kept in sync and never by orders; Trunk’s tiers step with order volume.

The comparison in one table

Trunk's figures read from its public App Store listing on 18 September 2026; complaint share calculated from the listing's own rating breakdown. Prices re-checked on 25 September 2026, including the higher-volume tiers on Trunk's own site. These move — the listing is linked from the Trunk alternatives page so you can check today's.

The honest summary

If you sell on marketplaces, this is not a close comparison and Trunk is your answer — we would say the same thing to a friend. The case for StockUnison is narrow and specific: everything is in Shopify, you want to see exactly what would change before it does, and you would rather not fund reach you never use.

Whichever you land on, pick one. If you are trialling a replacement with the incumbent still running, read what two inventory sync apps do to one count first — it is the commonest way an evaluation ends with numbers nobody can trust, and it looks like a fault in the new app when it is not.