Choosing · checked Oct 29, 2026, re-checked monthly
Shopper Zero or Shopify SimGym?
Both are worth knowing about. Shopify SimGym: Shopify's own research-preview app that runs AI shoppers with human-like personas through a Liquid storefront (one theme, or two themes side by side) to browse collections, view products and add to cart, then returns a key finding, storefront screenshots, session replays and Sidekick-written recommendations. [src: help.shopify.com/en/manual/online-store/simgym, apps.shopify.com/simgym; checked 29 Oct 2026] Shopper Zero: A mystery shopper for AI assistants: an AI shopper asks a US Shopify store what buyers ask and tries to buy, on the routes assistants use, and shows the owner where the sale was lost. Below are both prices, what each one does, and where each one wins, so you can decide without a sales call.
Shopify (developer address 151 O'Connor St, Ottawa, Canada); 'Currently in AI Research Preview' · 8 Dec 2025 on the App Store (Winter '26 Edition); open to all eligible merchants with no waitlist since 11 Mar 2026 (Shopify changelog); still labelled AI Research Preview on 29 Oct 2026. [src: apps.shopify.com/simgym, changelog.shopify.com; checked 29 Oct 2026]
Shopify SimGym
- Free monthly allowance: $0. An unstated number of simulations per month; renews on the first of the month; unused simulations do not roll over; a theme comparison uses about twice the allowance of a single-theme run. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Single-theme simulation beyond the allowance: $0.75 per run. One simulation (entire shopping journey, product discovery, or add-to-cart confidence) on one theme; the exact price is shown before a paid run and you can cancel without charge; billed on the Shopify bill only after the simulation completes successfully. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Theme comparison beyond the allowance: $1.50 per run. Two themes (the second must be a draft) with the same shoppers, a summary of which drove more add-to-carts, and recommendations per theme. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- App Store listing wording: 'Free to install. Additional charges may apply.'. 'Charges per simulation run. More details available in the app. All charges are billed in USD.' The listing itself gives no amounts. [src: apps.shopify.com/simgym; checked 29 Oct 2026]
zer0xception · October 2026
Shopper Zero
- Agent Test: $149, one time. Ten tasks, each run twice; the replay of every lost sale; the fixes in order; the buyer’s questions on every route; the Black Friday pre-flight; a free re-check within 14 days; the report the same day.
- Agent Watch: $99 a month per store. The same ten tasks every Monday, compared with the week before, with an email only when something gets worse. Cancel online at any time in two clicks; it runs to the end of the month paid for.
What each one does
| Shopify SimGym | Shopper Zero | |
|---|---|---|
| Checks set-up files and data | No | Yes |
| Drives a real browser | Yes | Yes |
| Adds to cart | Yes | Yes |
| Reaches checkout | No | Yes |
| Pays | No | No |
| Asks about delivery and returns | No | Delivery, returns, contact and discount, asked on seven routes |
| Re-tests every week | No | With Agent Watch, $99 a month |
| Replays with screenshots | Yes | Step-by-step screenshots, with the spot a sale was lost |
| Routes it covers | Liquid storefront pages only; Hydrogen and headless storefronts are not supported; no MCP, UCP or WebMCP [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026] | Your storefront pages in a real browser, plus llms.txt, agents.md, your UCP profile, WebMCP and your store’s own agent connection, read without buying |
Where Shopify SimGym wins
- Price: a free monthly allowance, then $0.75 per simulation or $1.50 per theme comparison; fifty-two weekly runs beyond the allowance would cost about $39 a year, against $149 once and $99 a month. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Built into Shopify: results and Sidekick recommendations live in the admin, and since the Fall '26 Edition Sidekick can propose a store change and test it with SimGym before you accept it, and you can set a shopping goal for a run; Shopper Zero hands you 'Copy for your developer'. [src: shopify.com/editions/fall2026, help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Tests a draft theme before you publish it, and compares two themes with the same shoppers; Shopper Zero tests only the live store. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Fast and unlimited: 1 to 5 minutes per run, as many runs as you pay for, with no human-review queue; Shopper Zero is capped at 20 human-checked tests a day. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Many personas who describe the experience in their own words, and you can rate each recommendation as helpful; Shopper Zero is one AI guest and publishes no shopper narrative. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Not US-only: reviewers are in Sweden, Germany, Japan, New Zealand, Canada and the US; Shopper Zero is US-only at launch. [src: apps.shopify.com/simgym/reviews; checked 29 Oct 2026]
- A public track record: 40 reviews and ten months live, against a new product with none. [src: apps.shopify.com/simgym; checked 29 Oct 2026]
Where Shopper Zero does more
- Reaches the checkout page; SimGym's help page lists add-to-cart as the last shopper action and a Feb 2026 third-party review says it 'does not test checkout flow beyond the add-to-cart event'. [src: help.shopify.com/en/manual/online-store/simgym, ecommercefastlane.com/simgym-review; checked 29 Oct 2026]
- Tests an AI shopping agent as a first-time guest on ten product-based tasks run twice, and asks the buyer's questions on seven routes; SimGym tests human-persona conversion only, with no policy questions and no agent routes. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Nothing installed and no Shopify Network Intelligence, Liquid-theme or password-page requirement; it visits the public storefront like any guest. [src: help.shopify.com/en/manual/online-store/simgym eligibility section; checked 29 Oct 2026]
- Agent Watch runs every Monday with a what-changed comparison and an email only when something gets worse; SimGym runs only when you click Run and keeps a history with no scheduling or alerts. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
- Fixes ranked by how many tasks they stopped, with the exact spot a sale was lost, 'Copy for your developer' and a Black Friday pre-flight (agent routes, robots.txt, cart.js fee check). [src: help.shopify.com/en/manual/online-store/simgym (no equivalents); checked 29 Oct 2026]
- A person approves every report; SimGym reviews report false positives (a purchasable variant called out of stock, a working footer link flagged, findings from a stale snapshot) and Shopify replied that it is working to reduce them. [src: apps.shopify.com/simgym/reviews, 14 Aug, 19 Jul, 30 Jun 2026 reviews; checked 29 Oct 2026]
- Stated 90-day screenshot deletion; SimGym's help page states no retention period. [src: help.shopify.com/en/manual/online-store/simgym; checked 29 Oct 2026]
Who Shopify SimGym suits. A Shopify merchant on a Liquid theme who wants a cheap, in-admin, before-you-publish read on which theme or layout change gets more add-to-carts.
Who Shopper Zero suits. A US Shopify store that wants to know, with a replay, whether an AI assistant can actually buy from it before Black Friday, and what to fix first.
Reviews: 2.8 from 40 reviews (11 five-star, 5 four, 7 three, 6 two, 11 one-star); newest 2 Oct 2026. Recurring complaints: false positives, unclear credits, no export, no persona customisation, errors on run; Shopify replied to several on 26 Aug 2026. [src: apps.shopify.com/simgym, apps.shopify.com/simgym/reviews; checked 29 Oct 2026] Shopper Zero launched in October 2026 and has no public reviews yet. Not verified: Size of the free monthly allowance: the help page does not state it and the listing says 'more details available in the app'. Whether shoppers run in a real browser: Shopify does not say; it produces storefront screenshots and session replays. Checkout: the help page simply stops at add-to-cart; the explicit 'does not test checkout beyond add-to-cart' line is from a Feb 2026 third-party review. Fall '26 Edition details reported in mid-October notes (early access, desktop only, labelled tested only when the copy scores a higher add-to-cart rate) could not be confirmed on a Shopify help page on 29 Oct 2026; only the two Editions-page lines were found, and the Sidekick help page does not mention SimGym. A Feb 2026 third-party review quoted $10 per simulation; the help page's $0.75 and $1.50 supersede it. The listing shows a 'Based in India' badge beside the Ottawa developer address; this looks like a locale artifact. The claim that personas draw on billions of Shopify purchases is third-party reporting of Shopify's product lead, not a Shopify page.
Our limits, stated plainly
- Shopify stores selling to US customers first. Other platforms are read for the buyer’s questions but not yet sold to.
- The shopper does not use WebMCP or UCP to buy; it walks the store’s pages the way a browsing assistant does, and reads the agent routes without buying through them.
- Results are not a score out of 100. They are tasks completed, lost, or not counted.
- Screenshots are deleted 90 days after each report.
- Launched in October 2026; no public reviews yet.
Sources, checked Oct 29, 2026: https://apps.shopify.com/simgym, https://apps.shopify.com/simgym/reviews?sort_by=newest, https://help.shopify.com/en/manual/online-store/simgym, https://changelog.shopify.com/posts/shopify-simgym-is-now-available-in-ai-research-preview-for-all-eligible-merchants, https://www.shopify.com/editions/fall2026, https://help.shopify.com/en/manual/ai-powered-tools/sidekick, https://ecommercefastlane.com/simgym-review/. Prices are from the maker’s own pages or App Store listing and can change; tell us at hello@shopperzero.com if one is out of date and we will fix it within a week.