You installed the app. It's in your admin. You're being billed for it. The storefront looks exactly the same as before.

This happens constantly on Shopify, and it is usually not the app's fault. It's usually a documented platform behavior that nobody surfaced at install time.

Shopify's help center describes three ways an app can integrate with a theme: app blocks, app embeds, and code added directly to theme files. These differ in more than placement — they differ in which themes support them, whether they're on by default, and what they leave behind when you uninstall.

Working out which of the three you're dealing with usually produces the answer. Below: how to tell, and how to use the same distinction when choosing apps in the first place. Research date: September 1, 2026.

The short version

A chat widget, analytics tag, or anything without a specific position isn't working? App embeds are almost certainly still off. Shopify states that app embed blocks are deactivated by default after an app is installed. You have to flip the toggle in the theme editor.

Can't add a size chart or review widget to your product page? Your theme is probably vintage architecture. App blocks require Online Store 2.0 or newer.

Everything vanished after you switched themes? That's correct behavior. Shopify: if you change your published theme, you'll need to re-activate those apps in your new theme, as they won't be active by default.

Uninstalled an app and the code is still there? That app injected code into your theme rather than using a theme app extension. You can check for this before installing.

The three integration methods

App blocks

Added as blocks within a section, or as sections within a template, so app functionality lands exactly where you want it. Add, remove, reposition, and configure them from the theme editor.

Reviews, size charts, trust badges — anything where placement matters — works this way.

Theme support is conditional. Shopify's help center states app blocks can only be used with compatible themes, and its theme architecture comparison table marks "Enhanced app support" — which covers both app blocks and app embeds — as unsupported (✘) for vintage themes.

There's a finer constraint too: even on Online Store 2.0, not every section supports app blocks. In sections that do, an Apps entry appears in the block picker. If it doesn't appear, that section isn't compatible. Which sections qualify depends on the theme's own implementation, so you're checking the theme's documentation or asking the theme developer.

App embeds

Elements that float or overlay on the theme, or that add code without being visible at all — chat bubbles, analytics, tracking pixels.

Unlike app blocks, these work with any theme version, vintage included.

Shopify's own documentation disagrees with itself here, which is worth knowing. The theme architecture comparison table marks "Enhanced app support" — described as covering both app blocks and app embeds — as unsupported on vintage. The apps help page and shopify.dev both say app embed blocks can be used with any theme version. The comparison table is almost certainly the imprecise one, but if you need certainty about a specific app on a vintage theme, ask its developer before installing.

And they arrive switched off. Open the theme editor, click the App embeds icon in the sidebar, toggle the app on, save. Miss this and you get the classic "compatible theme, nothing happens" state.

One useful capability here: if you run multiple markets, app embeds can be customized per market. You can activate a chat app for North America only, or give different markets different embed settings, by selecting the market from the theme editor's dropdown before configuring.

Code added to theme files

Some apps inject code directly into your theme. After install you get onboarding instructions telling you to edit theme code yourself to place the functionality.

If your theme offers a Custom Liquid section, you can often paste the app's code there instead of editing theme files directly.

This is the method that leaves residue.

Determining your theme's architecture

Shopify's documented check:

1. Go to Online Store in your admin
2. Click Edit theme on the theme in question
3. Open Products → Default product
4. Look below the section list in the sidebar for an Add section button

Button present means sections on every page — Online Store 2.0 or newer. Absent means vintage.

Vintage themes split further into sectioned and non-sectioned. Open the code editor: files in the Sections directory means sectioned; empty means not.

One more wrinkle worth knowing. Shopify notes that in limited cases, parts of a theme support features that others don't — your product templates might allow adding and removing sections while your collection templates don't. That happens when JSON templates exist for some pages and not others, typically from a partial theme migration or from a theme sourced outside the Theme Store whose developer didn't include JSON templates throughout.

Also relevant to app compatibility: vintage themes aren't available in the Theme Store at all, and Shopify's free vintage themes receive no updates beyond security fixes.

What survives uninstall, and what doesn't

This is where the distinction stops being trivia and starts being procurement criteria.

Per Shopify's developer documentation, apps built on the theme app extension framework don't edit theme code. Assets — CSS, JavaScript, static content — are hosted on Shopify's CDN rather than written into your theme files. That reduces the risk of an app introducing breaking changes.

Apps that inject code into theme files are different, and Shopify's own uninstall documentation says so:

Some apps add code to your online store theme that isn't automatically removed when you uninstall the app. Before uninstalling, review the app's listing on the Shopify App Store or contact the app developer to find out if any extra steps are needed.

Shopify is telling you to check before you uninstall, because it might not clean up.

There's a structural reason. In Shopify's developer community, the explanation given is that by the time the app/uninstalled webhook fires, the Admin API session has already been revoked — so the app cannot delete the theme files it created even if it wants to. Less negligence than architecture.

Shopify's other stated uninstall considerations:

• Uninstalling a paid app cancels future recurring charges, but you may still be billed for the current cycle
• External charges billed outside Shopify don't stop when you uninstall
• If the app holds inventory at a location, you must transfer or delete that inventory first
• Any automation, integration, or feature depending on the app stops working
• Some app data can't be recovered after uninstalling
• Reinstalling doesn't guarantee your previous settings or data come back

Script tags stop running March 1, 2027

The oldest integration method has an expiry date.

Shopify's developer changelog states that script tags are deprecated and will stop running on March 1, 2027. If an app uses a script tag to load JavaScript onto your storefront, it needs replacing before then.

Critically, the deprecation applies to all API versions — pinning to an older one doesn't defer it.

And the deadline arrives in two stages. From October 1, 2026, five months earlier, scriptTagCreate and scriptTagUpdate return user errors and the ScriptTag REST Admin API resource rejects POST and PUT. Existing script tags keep running until March 2027; creating or updating them stops well before that.

The replacement is app embed blocks, shipped inside a theme app extension.

The same direction shows up in the Built for Shopify requirements: an app meant to be used in a merchant's online store needs to use theme app extensions to build its theme-facing elements; it shouldn't add, remove, or edit a merchant's theme files; and it gets audited for Asset API usage when it applies for Built for Shopify status.

Those requirements carve out exception categories, though — page builders, apps that back up and restore entire theme files, SEO and content-locking tools, developer tooling. So a Built for Shopify badge is meaningful evidence on this specific point, not a guarantee. It isn't a general quality mark either, but for this one question it means more than most badges do.

What to check before installing

• Does the app render on the storefront, or is it admin-only?
• If storefront: app block, app embed, or manual theme code editing?
• If you're on a vintage theme, does the app support vintage themes at all?
• If a theme migration is planned, what will need re-activating afterward?
• Does the listing mention extra uninstall steps?
• Does it carry the Built for Shopify badge? (evidence it doesn't edit theme files)
• Multiple markets — do you need per-market activation?

Troubleshooting sequence

1. Open the theme editor, click App embeds, and toggle the app on if it's off. Save.
2. For positioned features, check whether the block picker shows an Apps entry. If not, that section doesn't support app blocks.
3. Check Products → Default product for the Add section button to determine your architecture version.
4. Did you switch published themes recently? If so, activations were reset by design.
5. Still nothing — check the app's listing and docs for whether manual theme code editing is required.

Two notes on the theme editor itself. The search bar in the block picker searches your installed apps, not the entire App Store — an app that doesn't appear either isn't installed or doesn't support that page type. And if an app is already installed on your theme, you can ask Sidekick to place its blocks for you with a prompt like "Add the size chart app block to my product page."

Bottom line

1. Most "app not showing" cases are a disabled embed, an incompatible theme, or a theme switch. Check the theme editor and your architecture version before you file a support ticket.
2. Every theme migration costs you a re-activation pass. Activations don't carry over. Budget for it.
3. The integration method determines your uninstall debt. Theme app extensions don't touch theme code. Direct injection does, and it stays. Checking the listing before you install is the cheapest possible mitigation.

And any app still relying on script tags is working against a March 1, 2027 deadline. For anything you plan to keep long-term, whether that migration is done is a legitimate selection criterion.