Time and fetch the page.
A single GET request to the storefront homepage. The test records TTFB, total transfer time, and the response headers. No login, no API token.
Free Shopify Speed Test · No signup, no API key
Shopify Speed Checker
Time to first byte, document weight, script count, render-blocking files, and the third-party hosts your homepage pulls from. Scored to 100, with the biggest weight offenders called out.
Here is what a real test returns.
A frozen run on glossier.com. Score is a composite of TTFB, document weight, render-blocking files, and third-party host count.
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PassTime to first byte
482 ms (good) -
WarnDocument weight
247 kB HTML (target: under 200 kB) -
WarnRender-blocking JS
6 blocking files in <head> -
3rd-partyHeaviest 3rd-party: Google Tag Manager
92 kB transferred · 7 child scripts -
3rd-party2nd heaviest: Klaviyo
61 kB transferred · 2 scripts, 1 popup -
PassCompression
brotli enabled (good)
Run your own test above to see the full third-party host breakdown for any storefront.
What the Speed Checker measures.
The test focuses on the levers a merchant can actually pull: weight, script count, third-party hosts, cache and compression headers.
- Time to first byte (TTFB). Server-side response time, the floor on every other metric.
- Document weight. Raw HTML size in kB before compression, and after brotli or gzip.
- Total scripts. Count of
<script>tags, split between first-party and third-party hosts. - Render-blocking JS and CSS. Files loaded in
<head>withoutasyncordefer. - Third-party hosts. Unique external domains the homepage loads from, ranked by transfer weight.
- Top weight offenders. The five heaviest individual third-party origins, with their child script count.
- Compression. brotli, gzip, or none.
- HTTP version. HTTP/1.1, HTTP/2, or HTTP/3 (QUIC).
- Cache headers. Cache-Control, Expires, and Age on the document response.
- Estimated LCP. A heuristic largest contentful paint based on hero image size and position.
How the Shopify Speed Test works.
Parse the document.
Count every script and stylesheet. Group by host. Identify render-blocking files in the head. Estimate transferred weight per third-party origin.
Score and rank offenders.
Composite score from TTFB, weight, third-party host count, and render-blocking files. Top five heaviest hosts and biggest blocking files are surfaced with one-line fixes.
When to run a Shopify speed test.
Quarterly performance audit.
Apps accumulate. Pixels stay behind. A quarterly run shows what new weight was added and which apps you stopped using but never uninstalled. The cleanup is a one-afternoon project that pays back forever.
Pre-launch performance check.
Before a marketing push, run the test. Make sure your homepage is under the budget you would expect a 2026 storefront to hit. A slow landing page wastes the paid traffic you are about to send to it.
Competitor speed benchmark.
Test the three best-known competitors in your category. The relative ranking tells you whether speed is even a differentiator in your market. Sometimes the winners are slow too. Sometimes they are 3x faster than you.
Third-party app diet.
The heaviest third-party hosts ranking is the single most actionable list on the report. Removing one heavy unused app often beats every other speed fix on the page.
What the Speed Checker does not measure.
Static analysis is fast and cheap. A few things require a full browser to capture.
- Core Web Vitals (LCP, INP, CLS). Lighthouse and field data from Chrome User Experience Report are the right tools for the official numbers.
- JavaScript-rendered weight. Anything injected by JS after page load is invisible. The reported weight is the initial HTML and discovered subresources.
- Real user monitoring. The test runs from one location and one network. Real users see different numbers from different regions, devices, and connections.
- Subsequent page loads. The test covers the homepage only. PDP, PLP, cart, and checkout perform differently.
- Visual progress. No filmstrip, no screenshots. The test is a numerical readout, not a visual replay.
- Server location. TTFB depends on the test runner's distance from the Shopify edge serving the response. Variations across runs are expected.
Frequently asked questions.
Is the Shopify Speed Test free?
Yes. Every test is free, with no daily limit, no signup, and no API key. Results come back in seconds.
How is this different from Google PageSpeed Insights?
PageSpeed Insights renders the page in a headless Chromium and runs Lighthouse, returning Core Web Vitals. The Speed Checker is a static analysis: TTFB, document weight, script count, third-party host count. Faster, narrower, and focused on the levers Shopify merchants can actually move.
What is a good TTFB for a Shopify store?
Under 400 milliseconds is good. Between 400 and 800 is acceptable. Above 800 is slow enough that conversion is starting to suffer. TTFB depends on the visitor's distance from Shopify's edge, so absolute numbers vary by region.
Why does my Speed score vary between runs?
TTFB and total transfer time naturally vary with network conditions and Shopify edge cache state. Document weight and script count are stable across runs. Re-run the test three times and average the volatile metrics.
How do I reduce third-party load on my Shopify store?
Start with the top three heaviest third-party hosts in the report. Audit each: do you still use the app it belongs to, can the script be deferred, can it be moved into a tag manager that lazy-loads. Removing one heavy app often beats every other speed fix.
Does the Speed Checker work on non-Shopify sites?
Yes. The checks are platform-agnostic. Any public website with HTML and script tags can be tested. The benchmarks are tuned for Shopify storefronts, but the raw numbers apply anywhere.
The rest of the forensic kit.
Five more free Shopify tools, same evidence-first approach.