TL;DR: You cannot see another Shopify store’s installed-app list in the admin, but the apps give themselves away in the page. Three free ways to see them: paste the URL into a Shopify app detector, view page source and search for app script domains, or use a browser extension like Wappalyzer or Koala Inspector. Then check which apps are the heaviest, because the app stack, not the theme, is usually what makes a store slow.
The first thing I open on a Shopify audit is not the theme. It is the app stack. In more than 100 audits the pattern holds: the store that feels slow is running 15 to 30 apps, each injecting a script the owner forgot was there. Whether you are sizing up a competitor or auditing your own store, the starting question is the same, what apps is this store actually running, and the answer is hiding in plain sight in the page.
Why what apps a store uses actually matters
Every Shopify app you install does something on the storefront, and most do it with third-party JavaScript. A reviews app loads a widget script. A popup app loads a builder. A page builder loads its runtime. A pixel loads a tracker. On the first, uncached visit, all of that JavaScript competes for one main thread on a mid-tier phone while your shopper stares at a white screen.
That is why the app list is the first read. It tells you, before you touch a line of Liquid, where the weight is. For a competitor it tells you their playbook: which reviews app, which upsell app, which email tool. For your own store it tells you what to cut. The theme gets blamed for slow Shopify stores far more than it deserves; the app stack is the usual culprit.
How do I see what apps a Shopify store uses?
There is no button in Shopify that reveals another store’s apps, because Shopify keeps a merchant’s installed-app list private. So every method reads the public page instead. Here are the three that work, fastest first.
Method 1: paste the URL into a Shopify app detector
The quickest way is a tool that fetches the page and matches the scripts against a library of known apps. Drop in any product or home page URL and it returns the apps it finds. My Shopify app detector goes a step further than a plain list: it estimates the blocking time each app adds and its typical monthly price, so you see not just what is installed but what it costs the page and the invoice.
Run the free Shopify app detector
The advantage of a paste-a-URL detector is that it installs nothing, works on a locked-down work laptop, and reads the same cold load a real first-time visitor gets.
Method 2: view the page source and read the app signatures
If you want to see the raw evidence, open the store, press Ctrl+U (Cmd+U on Mac) to view the page source, and search (Ctrl+F) for the script domains apps leave behind. Each app has a signature:
- Reviews:
static.klaviyo.comis email,judge.me,loox.io,okendo,yotpoare reviews. - Popups and upsells:
privy,justuno,rebuy,wisepops. - Page builders:
shogun,gempages,pagefly. - Analytics and pixels:
googletagmanager.com,hotjar,clarity.ms,connect.facebook.net.
Find the domain in the source and you have found the app. It is slower than a tool and you need to know the signatures, but it is undeniable proof and it costs nothing. This is also how the detectors work under the hood; they just match hundreds of signatures for you.
Method 3: use a browser extension
A middle path is a browser extension that reads the page for you. Wappalyzer is a general technology detector that catches many Shopify apps along with the theme and framework. Koala Inspector is a Shopify-specific extension that names the apps and theme a store runs. Both are free for basic use. The trade-off is that you have to install them, and an extension sees only the page you are on, not a cold load measured against Google’s thresholds.
How to check what apps your own store uses
For your own store, the admin looks like the answer and is not the whole one. Settings, then Apps and sales channels lists every installed app. That is the billing view. It does not tell you which of those apps injects a render-blocking script on your product page, and it happily lists apps you stopped using that are still loading their JavaScript on every visit, the classic orphaned-script problem I find in most audits.
To see the storefront cost, not the billing list, run your live URL through the app detector and read the blocking time column. That is the difference between knowing you have 22 apps and knowing which 4 of them are eating your Core Web Vitals.
Which of the apps is actually slowing the store down?
Once you have the list, count is the wrong metric. Blocking time is the right one. One well-built app that defers its script costs almost nothing; one badly-built app can add half a second of main-thread work on its own. Most CRO advice gets this backwards and tells you to just cut apps, when the real move is to measure cost per app and cut the heaviest.
To see the app-by-app cost on a real cold load, the first-visit scan renders the page frame by frame and attributes the blocking time to each app, and the wider mechanism, why third-party scripts wreck INP and how to defer them, is in my note on deferring third-party scripts.
What to do once you know
Knowing the list is step one. The fixes fall into three buckets. Cut the apps you no longer use, and confirm their scripts actually stopped loading, not just that the app is uninstalled. Replace the heaviest single-purpose apps with native code where you can; a surprising number of app jobs are a few lines of Liquid, which I cover in replacing Shopify apps with Liquid snippets. And defer what is left so it loads after the page paints instead of blocking it.
The takeaway:
- You cannot see a store’s app list in the admin, but the apps reveal themselves in the page source.
- Three free methods: a paste-a-URL app detector, viewing page source for script signatures, or a browser extension like Wappalyzer or Koala Inspector.
- Your admin app list is the billing view, not the storefront footprint; orphaned apps keep loading scripts after you stop using them.
- Judge apps by blocking time, not count. One heavy app can cost more than ten light ones.
- Cut, replace, or defer the heaviest, and re-check the cold load to confirm the weight is gone.
Kaspian Fuad is a Shopify developer and CRO consultant who builds, audits, and ships themes for DTC brands. 12 years in ecommerce, 100+ stores, Top Rated Plus on Upwork. See a recent theme and performance build, or book a free 30-minute call if you want a second pair of eyes on your app stack.