There's a familiar anxiety that comes with pushing a major storefront update live. You've rebuilt the navigation, refreshed the PDP layout, maybe overhauled the entire theme, and then you flip the switch and spend the next 72 hours watching your conversion rate like it's a patient in the ICU.
Shopify just built a tool designed to change that. It's called SimGym, and it might be one of the more genuinely interesting things to come out of the Winter '26 Edition.
What SimGym Actually Does
SimGym is a first-party Shopify app, built by Shopify, not a third-party, that sends AI-powered shoppers through your store before you publish changes to real customers. These aren't bots running random click patterns. Shopify trained the shopper personas on behavioral data from billions of real transactions across their platform, then tuned those personas to your specific store's customer behavior. The result is something closer to a focus group than a synthetic test.
The simulated shoppers browse your store, navigate collections, add items to cart, and surface friction points, the same hesitations and drop-offs a real customer would experience. At the end of a simulation, you get:
- A winning theme recommendation based on add-to-cart rate
- Cart value comparisons between variants
- Navigation path analysis showing where shoppers struggled
- Qualitative feedback synthesized into actionable recommendations
The current use case is theme-to-theme comparison: you run your live theme against an alternative in your theme library and see which performs better with simulated traffic before any real customer sees it.
Why This Matters for High-Growth Brands
For brands doing serious volume on Shopify, the cost of a failed redesign isn't theoretical. It's real revenue lost while you diagnose what went wrong. The traditional CRO approach involves running a live A/B test, accumulating enough statistical significance (often weeks of data), and then making a decision. That process requires sufficient traffic to work, demands patience, and still carries the risk of your worse variant bleeding conversions while the test runs.
SimGym inverts that workflow. You stress-test the change synthetically first, catching the obvious friction points, the broken navigation logic, the CTA placement that confuses people, and only push to live traffic once you have early signal that the direction is sound. Think of it the way Shopify describes it: a flight simulator for your storefront. Pilots don't learn to handle engine failure mid-flight. They simulate it first.
This is particularly valuable in a few specific scenarios we see often with our clients:
Pre-launch redesigns. You're rebuilding for Black Friday or a major product launch. The pressure to ship is real, but so is the cost of conversion regression. SimGym lets you validate the new direction before it counts.
Low-traffic stores testing big changes. Traditional A/B testing requires volume to reach statistical significance. A store doing 50,000 monthly sessions can run a meaningful test in a couple weeks. A store doing 8,000 sessions might wait two months for the same confidence level, if they ever get there. SimGym gives those stores a way to get directional signal that they otherwise couldn't access.
Navigation and structural changes. Element-level tests (a button color, a headline) are relatively low-risk. But restructuring your main navigation, consolidating collections, or rethinking your mobile PDP layout? Those are high-stakes decisions where synthetic validation before live exposure makes real sense.
What It Can't Do (Yet)
SimGym is currently in AI Research Preview, which means it's real and available, but it's v1, and Shopify has been transparent about its limitations.
Right now, simulations can only compare your active theme against another theme from your theme library. You can't test individual page elements, hero copy, or specific section layouts without duplicating your entire theme to change them. Checkout flows, pricing, discounts, and anything outside the theme are out of scope.
There's also the fundamental caveat that synthetic users aren't real users. Shopify notes that simulated results can differ from actual shopper behavior, and early reviews from merchants in the Research Preview have flagged some accuracy gaps, particularly on stores with unusual catalog structures. The research community has long observed that AI-generated user behavior can be overly idealized: synthetic shoppers don't get distracted, don't arrive with browser history that shapes their mood, and don't experience the friction of a slow mobile connection at the worst moment.
The right mental model: SimGym is an early signal, not a verdict. It's most powerful when it catches something you hadn't considered, like a navigation dead-end, a confusing collection hierarchy, or a CTA that the simulated shoppers consistently bypassed. It's not a final sign-off before a major deployment.
How to Get Access
SimGym is available on the Shopify App Store now, but access during Research Preview requires joining a waitlist. To be eligible, your store needs at least one product listing, two themes installed (including your published theme), and Shopify Network Intelligence (SNI) enabled. Once accepted, simulations run on a pay-per-credit model. Pricing details are visible inside the app after approval.
The Bigger Picture: Shopify Is Bringing CRO Native
What's worth paying attention to isn't just SimGym in isolation. It's what SimGym signals about where Shopify is taking the platform. For years, rigorous storefront testing was a specialist activity. You needed to know which third-party app to buy, how to set up proper A/B testing methodology, how to interpret results without getting fooled by novelty effects or seasonal variance. Shopify is now building that capability directly into the platform, designed to be accessible to merchants who never would have run a proper test before.
SimGym is also designed to work as the first stage in a two-step workflow alongside Rollouts, Shopify's new native A/B testing feature. The idea is straightforward: use SimGym to catch the obvious problems synthetically, then validate with real traffic through a staged Rollout. It's a pre-validation pipeline that didn't exist on the platform six months ago.
That's genuinely good for the ecosystem. More brands running more experiments means more conversion intelligence flowing through the platform, which feeds better AI models, which makes tools like SimGym more accurate over time.
For brands that are already running sophisticated CRO programs, SimGym doesn't replace your existing stack. But as a pre-validation layer before live testing, it's a meaningful addition to the toolkit, and one worth getting familiar with now, while it's still early enough to be ahead of the curve.
SimGym is available in AI Research Preview on the Shopify App Store. Access requires joining the waitlist.
If you're planning a major storefront update and want to build SimGym into your testing workflow, get in touch with the Conspire team. We've been working with the tool and can help you get the most out of it.
Native A/B Testing on Shopify: How Rollouts Works and What It Can't Do Yet