Website and SEO
The site check: speed, mobile, SEO and security in a real browser
How the site check loads your pages as a phone on 4G, what the six sections measure, how each finding tells you the cause and the fix, and when checks run on their own.
Updated · 4 min read
The site check opens your website the way most visitors do: in a real browser, on a mid-range phone, over a 4G connection. It loads your homepage and two more pages, records how long each part took and what the browser had to download, and turns that into a list of problems. Every problem says what is wrong, what is causing it, and how to fix it.
Where
- Web: open a domain and choose the Site check tab. Run a site check starts one; it takes a minute or two. The Monitoring page's Page performance panel shows every domain's latest speed score and links to this tab.
- API/MCP:
POST /api/domains/:id/site-check,GET /api/domains/:id/site-checks,GET /api/site-checks/:id; toolsrun_site_check,list_site_checks,get_site_check.
The phone we use
The same profile PageSpeed Insights uses for its mobile test: a 412 px wide screen, a processor four times slower than a laptop, and "slow 4G" (a 1.6 Mbps connection with a long round trip). Each page loads in a fresh browser with nothing cached, like a first-time visitor. Lab numbers move by a few hundred milliseconds from one run to the next, so compare trends rather than single runs.
The six sections
| Section | What it looks at |
|---|---|
| Speed | Main content (Largest Contentful Paint), first paint, how long the page is frozen (Total Blocking Time), layout shift, server response time, page weight. Then why: render-blocking files, oversized or old-format images, a lazy-loaded main image, JavaScript that downloads but never runs, uncompressed or short-cached files, third-party code, fonts that hide text, very large pages |
| Mobile | Sideways scrolling and the element that causes it, content cut off at the edge, links and buttons too small to tap, text under 12 px, form fields that make iPhones zoom, pop-ups covering the screen, a missing or zoom-blocking viewport tag |
| SEO | What search engines see on the finished page: HTTP errors, noindex, title, meta description, H1, canonical, language, broken structured data, text that only appears after JavaScript runs, images without alt text |
| Security | What a browser can see: HTTPS, mixed content, security headers (HSTS, CSP, nosniff, framing), a server announcing its version, and JavaScript libraries with published vulnerabilities (jQuery, Bootstrap, AngularJS, Lodash, Moment, Handlebars, DOMPurify, matched on the exact version the library reports). The section also shows the vulnerability count from DomainGuard's scans of your servers, with a link to the details |
| Accessibility | A quick automated axe-core pass over the homepage. The accessibility audit covers ten pages with evidence |
| Errors | Files the page asks for that are missing or failing, and JavaScript errors during the load |
Speed is scored the way Lighthouse scores a mobile run, on the same curves (Speed Index is the one metric we leave out). The other sections start at 100 and lose points for each problem: 20 for one marked "Fix first", 10 for "Worth fixing", 4 for "Minor".
Reading a finding
Each finding opens to show:
- What we measured, in numbers, against Google's thresholds where there is one.
- What is causing it: the specific image, script, element or setting, with the evidence we saw (file sizes, selectors, headers).
- How to fix it, in steps, and where a fix has a measurable payoff, roughly how much faster or smaller the page gets.
- The pages it was seen on.
Findings are ordered with "Fix first" at the top and, within that, the biggest savings first.
When checks run on their own
| Plan | Scheduled site checks |
|---|---|
| Free | On demand only |
| Starter | Weekly, on your automated domains |
| Pro, Enterprise | Daily, on your automated domains |
Anyone can run a check by hand, six an hour per account; checks cost no credits. A domain with its automatic checks paused is skipped.
Alerts
When a scheduled check finds a site has got slow on phones, you get an alert in the feed and a push: the main content now takes over 4 seconds where it used to be quicker, or the speed score fell 15 points or more to under 50. The comparison is against the middle of the last three checks, so one slow run does not set it off. The first scheduled check of a slow site says so once. Turn it off under Settings → Alerts → Site speed.
Limits
- Three pages per check: the homepage, then pages from different parts of the site, taken from the sitemap or, if there is none, from the homepage's links.
- The check follows the domain's own redirects but will not measure a different website the domain sends visitors to.
- A page that does not start loading within 60 seconds is reported as not loading; a page still downloading after 30 more seconds is measured as it stands and flagged.
- Pages behind a login are not checked.
Keep reading
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