Shopify speed test. App weight included.
Enter a Shopify URL, get Google PageSpeed data for all four Lighthouse categories, Core Web Vitals from real-world CrUX data, and a sorted table of which third-party Shopify apps are weighing the page down. No login. No email.
Shopify speed is app weight, not theme code.
Most Shopify stores score 20 to 50 on mobile PageSpeed, far below typical SaaS marketing pages that hit 80 plus. The reason is not bad theme code. Shopify's Dawn, Impulse, Prestige, and Horizon themes are well-engineered. The speed hit comes from the third-party app layer every growing store accumulates: reviews, email capture, live chat, subscriptions, upsell, page builders, SMS. Each app injects its own JavaScript bundle that runs on page load, blocks the main thread, and adds network round trips. The typical mid-market store runs 8 to 15 apps, and the cumulative JavaScript weight exceeds the theme itself by a factor of two to five.
The tool above uses the public Google PageSpeed Insights API, the same backend that powers the public PSI site and Google Search Console's Core Web Vitals report. Results include all four Lighthouse categories (Performance, SEO, Accessibility, Best Practices) plus field data from the Chrome User Experience Report when the URL has enough live traffic. Field data is what Google uses for ranking; lab data is useful for debugging.
The Shopify-specific third-party detector cross-references the PSI third-party summary against a list of 20 common Shopify apps and ranks them by script weight in kilobytes plus main-thread blocking time in milliseconds. Apps over 100 KB or 150 ms block-time are flagged in amber. This is the layer most competing speed tools skip: they show a generic third-party list without recognising which are Shopify apps versus Google Fonts versus analytics, which makes it hard to know where to start. Start with the biggest amber row.
Tools in the same cluster: Shopify development services for implementation help. XML sitemap generator for crawl-efficiency fixes. Schema markup generator for SEO structured data.
Six answers.
What is a good Shopify speed score?
Typical Shopify stores score 20 to 50 on mobile PageSpeed Insights out of 100, versus 40 to 70 on desktop. The benchmark is lower than most SaaS marketing sites because Shopify themes ship with jQuery, heavy third-party apps, and variant-selector JavaScript that block the main thread. Above 60 on mobile puts you in the top decile of Shopify stores. Below 30 is the danger zone where Core Web Vitals penalties kick in. The score itself matters less than Core Web Vitals (LCP, INP, CLS) which are actual ranking factors; treat the 0-100 score as a composite indicator and focus remediation on CWV.
Which Shopify apps slow down my store the most?
The tool ranks detected apps by kilobyte weight of their injected scripts. Common heavy apps by weight: reviews apps (Judge.me, Loox, Yotpo) at 50 to 200 KB each, email-capture apps (Klaviyo, Privy, Omnisend) at 30 to 150 KB, upsell and bundle apps (Bold, ReConvert) at 40 to 120 KB, and live chat (Gorgias, Tidio, Shopify Inbox) at 100 to 400 KB. The three worst offenders we routinely see: Yotpo loaded on the homepage, Shopify Inbox widgets auto-loaded on product pages, and page-builders like PageFly or GemPages that stack multiple runtime frameworks. The per-app weight table in the output tells you exactly which apps to audit first.
What is LCP and why does it matter for Shopify?
Largest Contentful Paint is the time in seconds from navigation to when the largest visible element finishes rendering. On most Shopify product pages the LCP element is the hero product image. Google ranks LCP below 2.5 seconds as good, 2.5 to 4 seconds as needs improvement, and above 4 as poor. LCP is the single highest-impact Core Web Vital for Shopify stores because it is usually fixable by image optimization: switch to responsive srcset, ship WebP, preload the hero image with fetchpriority high, and remove render-blocking third-party scripts from above the fold. The test result shows your exact LCP element and the breakdown of time spent on network, server, and render.
Does removing a Shopify app actually improve my speed score?
Usually yes, but the effect is nonlinear. Removing one lightweight app (under 20 KB) rarely moves the score more than 1 or 2 points. Removing one heavy app (Yotpo, PageFly, certain chat widgets) often moves the mobile score 8 to 15 points. The tool's per-app table shows both the raw script weight and a projected score change if that app were removed, calculated from the CPU-blocking time each script contributes. Before uninstalling an app, check whether its functionality can be replicated with native Shopify features or a lighter alternative; some apps are worth the weight, others replace a theme block you could ship for free.
Is CrUX field data more important than lab data?
For SEO, yes. Google uses Chrome User Experience Report (CrUX) field data to evaluate Core Web Vitals for ranking, not the lab-synthesized Lighthouse score. Field data is actual Chrome users visiting your site over the last 28 days, aggregated. Lab data is a single synthetic run from Google's test server, useful for debugging but not ranking. The tool surfaces both: CrUX LCP, INP, and CLS for field, and Lighthouse lab metrics beneath. A site can score 95 in the lab and still fail CWV in the field if real users are on slower devices than the test profile simulates.
Does this tool store my URL or results?
No. The test calls Google's public PageSpeed Insights API directly from your browser using CORS; DH never sees the URL or the result. The URL you tested, the scores, and the app weights all live in memory for this browser tab only. Running the test counts against Google's public PSI rate limit (25,000 queries per day globally), not any DH limit. The tool uses localStorage to remember your last tested URL for convenience, which you can clear by wiping browser data.
One test. Not enough.
Our Shopify engagements ship CWV-aware theme builds, app-audit sessions that quantify per-app removal value, server-side tracking to kill client-side script weight, and monthly CWV monitoring so regressions get caught the day they ship. Written plan in 2 weeks.