Homepages loading jQuery twice, by platform (Sept 2026, top 1M)
| Platform | Load two jQuery copies | Also load jQuery Migrate | Homepages loading jQuery |
|---|---|---|---|
| Shopify | 24.1% | 1.1% | 20,730 |
| Squarespace | 26.8% | 0.7% | 149 |
| Wix | 15.8% | 5.0% | 120 |
| Other/custom | 12.0% | 7.6% | 239,662 |
| WordPress | 10.2% | 76.4% | 89,554 |
| Webflow | 9.6% | 3.5% | 427 |
| All | 12.2% | 24.8% | 350,642 |
Source: PageSpeed Matters, Sept 2026. Squarespace, Wix and Webflow groups are small. jQuery Migrate is not counted as a copy.
Summary
jQuery is still one of the most widely loaded JavaScript libraries on the web. A page only ever needs one copy of it. A second copy means the browser downloads, parses and runs the same library twice, and the second copy can overwrite the first and break plugins that were attached to it.
We counted how often that happens in the top 1M. 42,874 homepages load jQuery twice: 12.2% of the 350,642 homepages that load jQuery at all, and 5.5% of all 782,850 top 1M homepages. Shopify homepages do it most often, and homepages with two copies pass Core Web Vitals less often.
What we measured
We looked at the HTTP Archive crawl from September 2026, mobile, which covers the top 1M sites by Chrome traffic, and at the script files each homepage requests.
A copy of jQuery means a script request for jquery.js, jquery.min.js, a slim build, or a versioned jquery file. A homepage loads jQuery twice when it makes two or more of those requests. jQuery Migrate, a helper that keeps old jQuery code working with newer versions, is not a copy of jQuery under this definition, so it is not counted as a duplicate.
Core Web Vitals pass rates come from Chrome UX Report field data where it is available. The pass-rate gap is a correlation only.
About one in eight jQuery homepages load it twice
Of 350,642 top 1M homepages that load a jQuery core file, 42,874 load two or more copies. That is 12.2%, about one in eight. Across all 782,850 top 1M homepages, including those without jQuery, it is 5.5%.
Popularity barely changes the rate. 11.8% of 2,390 jQuery homepages in the Top 10K load two copies, against 12.6% of 26,412 in the Top 100K and 12.2% of 321,840 in the rest of the top 1M. Unlike many maintenance problems, this one is just as common on large, well-resourced sites as on small ones.
That suggests duplicates are not mainly about neglect. They usually appear when different parts of a site each bring their own copy: a theme, an app or plugin, a tag manager snippet, or a widget from a third party.
12.2%
Share of the 350,642 top 1M homepages that load jQuery which load two or more copies of it.
Shopify homepages are twice as likely to load two copies
Among the large platforms, Shopify stands out. 24.1% of 20,730 Shopify homepages that load jQuery load two copies, about twice the rate of WordPress (10.2% of 89,554) and other or custom platforms (12.0% of 239,662). Webflow sits at 9.6% of 427.
The likely reason is how Shopify stores are built. A theme may ship its own jQuery, and apps added to the store can inject their own copy as well, with no single place that checks whether jQuery is already on the page.
Squarespace (26.8%) and Wix (15.8%) also show high rates, but those groups are small, at 149 and 120 jQuery homepages, so the figures are less reliable than the larger platforms.
jQuery Migrate is a WordPress pattern
WordPress has a different habit. 76.4% of WordPress homepages that load jQuery also load jquery-migrate, against 7.6% on other platforms and 1.1% on Shopify. WordPress has long loaded Migrate alongside jQuery for themes and plugins that rely on older jQuery code.
Migrate is a separate helper, not a second jQuery, so we do not count it as a duplicate. If we did, the duplicate rate would rise to 33.5%. It still adds a request, and many sites can drop it once their themes and plugins no longer need it.
Two copies go with lower Core Web Vitals pass rates
Homepages that load two copies of jQuery pass Core Web Vitals less often. 40.1% of the 34,810 such homepages with Chrome UX Report data pass, against 47.5% of the 239,941 jQuery homepages with a single copy.
This is a correlation, not proof that the second copy causes the gap. A homepage with duplicate jQuery usually has several scripts arriving from different sources, and that tends to go with heavier JavaScript overall. The duplicate is a useful sign that scripts reach the page from several places with no one checking the total.
What this means for your site
Checking takes a minute. Open your homepage in your browser's developer tools, go to the network panel, reload, and filter for "jquery". More than one jquery.js or jquery.min.js file means a duplicate.
To fix it:
- Find where each copy comes from: the theme, an app or plugin, or a hard-coded script tag.
- Keep one copy, ideally the one your theme or platform already provides, and remove or disable the others.
- Test the features that depend on jQuery, such as sliders, menus and forms, after each change.
- On WordPress, check whether your theme and plugins still need jquery-migrate before removing it.
Then rerun PageSpeed Insights to see how much JavaScript the page no longer has to process.
Sources
- HTTP Archive crawl of the top 1M sites by Chrome traffic, September 2026, mobile
- Chrome UX Report (CrUX) field data, September 2026
- Chrome UX Report documentation: https://developer.chrome.com/docs/crux
Embed this research
Paste this on your site to embed the chart. It links back to the source automatically.
<iframe id="psm-duplicate-jquery-statistics" src="https://www.pagespeedmatters.com/embed/data-studies/duplicate-jquery-statistics" width="100%" height="600" style="width:100%;border:1px solid #E2E3E1;border-radius:12px" loading="lazy" title="Duplicate jQuery Statistics: 12.2% Load Two Copies - PageSpeed Matters"></iframe>
<script>window.addEventListener("message",function(e){if(e&&e.data&&e.data.psmEmbed==="duplicate-jquery-statistics"&&e.data.height){var f=document.getElementById("psm-duplicate-jquery-statistics");if(f){f.style.height=e.data.height+"px";}}});</script>
<p style="font:14px/1.5 system-ui,sans-serif">Source: <a href="https://www.pagespeedmatters.com/resources/data-studies/duplicate-jquery-statistics">Duplicate jQuery Statistics: 12.2% Load Two Copies - PageSpeed Matters</a></p>
Frequently asked questions
How common is loading jQuery twice?
42,874 top 1M homepages load two or more copies of jQuery. That is 12.2% of the 350,642 homepages that load jQuery and 5.5% of all 782,850 top 1M homepages.
Which platforms load duplicate jQuery most often?
Among large platforms, Shopify: 24.1% of Shopify homepages that load jQuery load two copies, against 10.2% of WordPress homepages and 12.0% of other platforms.
Does jQuery Migrate count as a duplicate jQuery?
Not in this study. jQuery Migrate is a separate helper, loaded by 76.4% of WordPress homepages that use jQuery. Counting it as a copy would raise the duplicate rate to 33.5%.
How do I check if my site loads jQuery twice?
Open your browser's network panel, reload the page and filter for jquery. More than one jquery.js or jquery.min.js file means the page loads a duplicate.
A duplicate library is usually one leftover script tag or app setting, and removing it cuts JavaScript the browser never needed to run. Need help with this? See our website maintenance services.