Shopify apps vs WooCommerce plugins

Neither platform does everything out of the box. Reviews, subscriptions, bundles, shipping rules: sooner or later you add them. WooCommerce calls these add-ons plugins. Shopify calls them apps. They sound like two names for the same thing, but they work in different ways, and the difference shows up in your day-to-day running of the store.

Inside the store vs beside it

A WooCommerce plugin is PHP code that WordPress loads on every request, in the same place as WooCommerce itself. It can read and write any table in your database, hook into any part of the page or checkout, and change what other plugins do. From the server's point of view, plugins and core are all one program.

A Shopify app mostly runs somewhere else, on servers its developer operates. It talks to your store through Shopify's API, and only with the permissions you approved when you installed it: read products, edit orders, and so on. When it needs to show something to shoppers or change checkout, it goes through set extension points: theme app blocks for the storefront, and checkout extensions and Functions for checkout.

Everything else in this post comes from that one difference.

When two add-ons collide

Plugins share a single program, so they can break each other. Two plugins load different versions of the same library. One changes a hook's output in a way the next doesn't expect. An update to one plugin brings down a page that belongs to another. The usual fix is to turn plugins off one at a time until the problem goes away, ideally on a staging copy of the site and not the live store.

Shopify apps can't reach into each other's code, so that kind of crash is rare. Apps can still overlap, though. Two apps can both add discounts, both put a widget in the same spot, or both edit the same product fields. The store won't go down, but you can still end up with results you didn't expect, and working out which app did what still takes time.

Speed

On WooCommerce, every active plugin adds work to the server, often on every page load, plus whatever scripts and styles it puts into the page. A store with dozens of plugins can get slow before anyone notices.

On Shopify, apps can't slow down Shopify's servers, but many still add JavaScript to your storefront. Every tracking pixel, pop-up and chat widget is more for the shopper's phone to download. Apps built on theme app blocks load only where you place them, which helps. It's worth checking your storefront speed after each install either way.

Uninstalling

Deactivating a WooCommerce plugin stops its code running. Whether it cleans up after itself is up to the developer: settings, custom tables and scheduled tasks often stay in your database unless the plugin removes them on deletion.

Uninstalling a Shopify app removes its API access straight away, and theme app blocks go with it. Older apps that pasted code straight into theme files can leave snippets behind, which you'll have to find and delete by hand. When comparing apps, it's worth preferring ones that use app blocks.

When the developer walks away

This is where the difference matters most, and it cuts both ways.

• A WooCommerce plugin keeps running after its developer stops maintaining it. The code is on your server. But it also stops getting security fixes, and outdated plugins are the most common way WordPress sites get compromised. Sooner or later you'll need to replace it or patch it yourself.
• A Shopify app can stop working the day its developer shuts it down, because it runs on their servers. Any data it kept only on those servers may go with it. Data an app stored inside Shopify, such as metafields, orders and products, stays in your store.

Before relying on either, ask where your data lives and what you'd do if the add-on disappeared tomorrow.

Finding, vetting and paying

WooCommerce plugins come from the WordPress.org directory, the official WooCommerce marketplace and independent sellers. Many are free, with paid "pro" versions often sold as yearly licences that you renew to keep getting updates and support. Quality varies widely, so check when a plugin was last updated, its reviews, and whether it has been tested with your version of WooCommerce.

Shopify apps come from the Shopify App Store. Apps are reviewed before they're listed there, and most are billed through your Shopify invoice, often as a monthly subscription that stops when you uninstall. Review isn't a guarantee of quality, but it does set a minimum bar. For current pricing on either side, check each developer's listing, because it changes often.

Building your own

If nothing on the market fits, both platforms let you build for your store alone. On WooCommerce that's a custom plugin, or a few lines in a child theme: full access, and full responsibility. On Shopify it's a custom app, created in your admin or through a Partner account, with the same API permissions and extension points as public apps. It's more setup up front, but the result can't break the rest of your store.

Which model is better?

WooCommerce plugins suit you if you want total control and have someone who can test updates and dig into conflicts when they happen.

Shopify apps suit you if you'd rather add features without worrying that they'll break each other, and you're comfortable depending on each app's developer to keep it running.

Either way, fewer add-ons, each doing one job well, beats a long list of overlapping ones.

Giraffe Shipping is built this way: your shipping rules run inside Shopify checkout, with no code and no theme edits, so uninstalling it leaves nothing behind.

← Previous: changing checkout on each. Or start from part 1: what they actually cost.