duplex.sk website review

36 files are served with short cache lifetimes, so returning visitors download them again (1.3 MB).

15 files block the first paint until they finish downloading. Deferring or inlining them could save about 2.1 s.

4 images could be 431 KiB smaller with modern formats (WebP or AVIF) and sizes that fit a phone screen. Google estimates it would make the page about 1.7 s faster on a phone.

Your mobile performance score is 61. Pages that score under 90 lose visitors before the first paint.

3 third-party services load with your homepage (Google CDN, Other Google APIs/SDKs and Google Fonts), adding 842 KiB and 674 ms of main-thread time.

Google CDN costs a phone 601 ms of main-thread work and 742 KiB of downloads while your page loads. Loading it after the page is usable, or only on the pages that need it, takes that off the critical path.

About 383 KiB of JavaScript is downloaded but never used on this page. Google estimates it would make the page about 150 ms faster on a phone.

About 102 KiB of CSS is downloaded but never applied on this page. Google estimates it would make the page about 300 ms faster on a phone.

Web fonts hide text while they load. Setting font-display: swap shows text immediately (about 400 ms).

A phone's processor spends 3.3 s on main-thread work while loading, 1.7 s of it running JavaScript. Above 2 s, taps and scrolls feel sluggish.

8 long tasks block the main thread while loading, the longest for 198 ms. During a long task the page ignores taps.

Polyfills for old browsers add 9 KiB JavaScript that modern phones do not need.

Critical files load one after another instead of in parallel (3 chains). Preconnecting to key origins and preloading the hero image shortens the chain.

Scripts make the browser recalculate the layout repeatedly while the page loads, which wastes processor time on phones.

Your largest element takes 6.8 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the text “Realizujeme všetky typy fotovoltických inštalácií”. Most of its time is element render delay (2.8 s).

The page becomes fully interactive after 12.6 s. Good is under 3.8 s.

Visually, the page fills in at 5.4 s (Speed Index). Good is under 3.4 s.

Scripts block taps and scrolling for 307 ms in total while the page loads. Good is under 200 ms.

The first text or image appears after 2.0 s on a phone. Good is under 1.8 s.

The layout shifts by 0.106 while loading, so content jumps under the reader's thumb. Good is under 0.1.

Chrome's UX Report (opens in a new tab) has too little real-visitor traffic for this site, so the figures here are lab measurements from Google's test phone on a throttled 4G connection.

Your homepage downloads 2.5 MB in 55 requests on a phone: images 846 KiB (9), scripts 844 KiB (19) and fonts 363 KiB (7). Under 2 MB keeps phones on slow connections fast.

By the Sustainable Web Design model, a visit to your homepage emits about 0.72 g of CO₂e: 86.1 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

4 text elements don't have enough contrast against the background to read easily, especially outdoors on a phone.

[role="img"] and [role="image"] elements must have alternative text: 2 elements on the page fail this check, rated serious by axe-core.

1 frame has no title, so screen-reader users cannot tell what it contains.

1 tap target is too small or too close together to hit reliably with a finger.

Landmarks should have a unique role or role/label/title (i.e. accessible name) combination: 1 element on the page fails this check, rated moderate by axe-core.

1 form field has no label, so screen readers announce an empty box and autofill guesses.

Headings skip levels (h1 → h3 and h3 → h5), which makes the page harder to scan with a screen reader.

Your title is only 14 characters: “Domov - Duplex”. Between 30 and 65 characters leaves room to say what you do and for whom.

There are 2 <h1> headlines (“Realizujeme všetky typy fotovoltických inštalácií” and “Realizujeme inštaláciu optických a mobilných sietí”). One clear main headline is easier for people and search engines.

The homepage links to 26 pages on duplex.sk and 4 external pages.

Your Organization JSON-LD is missing sameAs (social profiles), description and contact details. These are the facts AI assistants use to describe a business and to tell it apart from others with a similar name.

There is no /llms.txt, a short Markdown guide to your key pages for AI tools (llmstxt.org). It is optional and few AI tools read it yet, so treat it as a cheap extra.

Your homepage links to /ochrana-osobnych-udajov, which answers with an error. Visitors hit a dead end and search engines drop it.

/technicke-vybavenie-na-prenajom and /technicke-vybavenie all use the title “Technické vybavenie - Duplex”. Search engines can't tell which page to show for a search, so each competes with the others.

/telekomunikacie, /energetika, /stavebnictvo, /technicke-vybavenie-na-prenajom, /technicke-vybavenie-na-prenajom/pracovne-plosiny and /technicke-vybavenie-na-prenajom/zemne-prace and 3 others have no meta description, so Google writes the search snippet from whatever text it finds.

Your homepage links to 1 page by a URL that isn't its canonical one, for example /technicke-vybavenie, whose canonical is /technicke-vybavenie-na-prenajom. Linking straight to the canonical URL saves crawlers a detour and keeps ranking signals on one address.

We fetched 10 pages linked from your homepage and read each the way a search engine does.

4 images failed to load on a phone, for example https://duplex.sk/wp-content/uploads/2023/10/duplex_logo.svg.

2 of 9 tappable elements near the top of the page are smaller than 24 px, hard to hit with a thumb.

1 error was logged to the browser console while the page loaded, for example “Failed to load resource: the server responded with a status of 429 ()”.

1 link from your homepage to your own site is broken, for example https://duplex.sk/ochrana-osobnych-udajov/ (404).

No Strict-Transport-Security header, so browsers may still try plain http first on a return visit.

No Content-Security-Policy header, the main browser-side defence against injected scripts.

Neither X-Frame-Options nor a CSP frame-ancestors policy is set, so any site can embed yours in a frame.

X-Content-Type-Options: nosniff is missing, so browsers may guess file types.

No Referrer-Policy header, so full URLs can leak to the sites you link to.

No Permissions-Policy header to switch off camera, microphone and location for embedded content.

There is no /.well-known/security.txt telling researchers how to report a security problem to you.

duplex.sk has no CAA record, so any certificate authority may issue a certificate for it. A CAA record naming your provider (for example letsencrypt.org) closes that door.

On a phone, there is no call to action on the first screen: visitors have to scroll to find out what to do next.

We found no call-to-action buttons or links (such as “Book a demo” or “Get a quote”) anywhere on the homepage.

No testimonials, customer logos, ratings or customer counts on the homepage: nothing tells a new visitor that others already trust you.

Your homepage shows a map but no LocalBusiness JSON-LD, so Google and AI assistants have to guess your address, hours and phone from the page text.

No analytics or tag manager detected in the HTML, so you can't measure whether any of these fixes work.

The homepage shows no opening hours. If customers visit or call, show when.

No guarantee or risk reducer (money-back, free trial, no credit card) is mentioned, which is often what tips a hesitant visitor.

The homepage carries about 369 words of visible text.

duplex.sk has no DMARC record, so nothing tells receivers what to do with mail that fails SPF or DKIM. Gmail and Yahoo require DMARC from bulk senders.

Your SPF record doesn't end in -all or ~all, so it doesn't stop other servers sending as you: “v=spf1 a mx include:_spf.m1.websupport.sk ?all include:mail.zendesk.com ?all”.

Email authentication: SPF record 25 points, plus 15 when it ends in -all (10 for ~all); DMARC record 25, plus 25 for a reject policy (15 for quarantine); a DKIM key on a common selector 10.

No known cookie consent tool loads with the page. Some sites build their own banner, and some only show one to visitors from the EU.

Loading the homepage contacts 4 hosts run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.