zener.es website review

68 images could be 1.3 MB smaller with modern formats (WebP or AVIF) and sizes that fit a phone screen. Google estimates it would make the page about 3.0 s faster on a phone.

15 files block the first paint until they finish downloading. Deferring or inlining them could save about 1.3 s.

Your mobile performance score is 65 (desktop: 90). Pages that score under 90 lose visitors before the first paint.

About 153 KiB of JavaScript is downloaded but never used on this page. Google estimates it would make the page about 750 ms faster on a phone.

Web fonts hide text while they load. Setting font-display: swap shows text immediately (about 500 ms).

35 KiB could be saved by minifying JavaScript.

About 14 KiB of CSS is downloaded but never applied on this page. Google estimates it would make the page about 150 ms faster on a phone.

4 KiB could be saved by minifying CSS.

1 third-party service load with your homepage (jQuery CDN), adding 34 KiB and 93 ms of main-thread time.

1 long task block the main thread while loading, the longest for 51 ms. During a long task the page ignores taps.

Desktop scores 90 but mobile only 65. A gap that wide usually means heavy scripts and images that hit phones hardest.

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.

Real Chrome users on phones do not pass Google's Core Web Vitals on this page (28-day field data from the Chrome UX Report (opens in a new tab)). Google uses this in ranking.

Your largest element takes 10.3 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the text “La experiencia nos hace líderes en instalación y mantenimie…”. Most of its time is element render delay (4.2 s).

The page becomes fully interactive after 10.5 s. Good is under 3.8 s.

Visually, the page fills in at 7.3 s (Speed Index). Good is under 3.4 s.

Real visitors wait 2.6 s for the largest content to appear (75th percentile). Good is under 2.5 s.

Real visitors see the first content after 2.3 s (75th percentile). Good is under 1.8 s.

166 images have no width and height attributes, so the layout jumps as each one loads.

The first text or image appears after 2.3 s on a phone. Good is under 1.8 s.

Over the last 25 four-week periods to 2026-10-24, real Chrome visitors' tap response (inp) went from 83 ms to 89 ms at the 75th percentile (Chrome UX Report (opens in a new tab) history).

Over the last 25 four-week periods to 2026-10-24, real Chrome visitors' largest content (lcp) went from 2.3 s to 2.3 s at the 75th percentile (Chrome UX Report (opens in a new tab) history).

2 images weigh 1.7 MB together. On a phone connection a single image that size takes seconds.

3 images are downloaded at several times the size a phone draws them, for example unete-a-nuestro-equipo-home.png at 1,920 px wide, shown at 390 px. Resized copies would save about 522 KiB.

Your homepage downloads 3.7 MB in 141 requests on a phone: images 3.3 MB (106), scripts 338 KiB (19) and stylesheets 49 KiB (14). Under 2 MB keeps phones on slow connections fast.

12 images (2.5 MB) are JPEG, PNG or GIF. The same pictures as WebP or AVIF are usually much smaller at the same quality, and every current browser shows them.

10 images further down the page (522 KiB) download before anyone scrolls to them. Adding loading="lazy" lets the first screen load first.

By the Sustainable Web Design model, a visit to your homepage emits about 1.04 g of CO₂e: 125.3 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

24 tap targets are too small or too close together to hit reliably with a finger.

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

<html> element must have a lang attribute: 1 element on the page fails this check, rated serious by axe-core.

4 images have no alt text, which hurts accessibility and image search.

All page content should be contained by landmarks: 88 elements on the page fail this check, rated moderate by axe-core.

The page has no <main> landmark, so screen-reader users cannot jump straight to the content.

The viewport tag blocks pinch-zoom, which low-vision visitors rely on.

5 visible links have no text or label, so screen readers cannot say where they go.

The <html> element has no lang attribute, so screen readers may read the page in the wrong voice and accent.

Structured data found (WebSite) but with 1 problem, for example “WebSite: missing name”.

No Open Graph image, so links shared on LinkedIn, Slack or Facebook show no preview picture.

7 links use generic text like “click here” or “learn more”, which tells Google nothing about the page behind them.

1 link has no real href, so search engines can't follow it.

Your <h1> is empty.

The homepage links to 93 pages on zener.es and 7 external pages.

There is no Organization (or LocalBusiness) JSON-LD, so search engines and AI assistants have no machine-readable facts about who runs the site: its name, logo, profiles and contact details.

There is no https://www.zener.es/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.

https://www.zener.es/es/lineas-de-negocio and https://www.zener.es/es/lineas-de-negocio/telecomunicaciones all use the title “Instalaciones de Telecomunicaciones - ZENER”. Search engines can't tell which page to show for a search, so each competes with the others.

https://www.zener.es/es/lineas-de-negocio and https://www.zener.es/es/lineas-de-negocio/telecomunicaciones use the same meta description. A description written for each page earns more clicks.

Your homepage links to 1 page by a URL that isn't its canonical one, for example https://www.zener.es/es/lineas-de-negocio, whose canonical is https://www.zener.es/es/lineas-de-negocio/telecomunicaciones. Linking straight to the canonical URL saves crawlers a detour and keeps ranking signals on one address.

https://www.zener.es/es/zener/historia took over 3 s to send its HTML from our server.

We fetched 15 pages linked from your homepage (of 41 found) and read each the way a search engine does.

45 of 51 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 404 ()”.

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.

Social proof on the homepage: 1 trust badge. Pairing it with named testimonials or customer logos makes it far more convincing.

No phone number or email link on the homepage, so ready-to-buy visitors have one fewer way to reach you.

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 693 words of visible text.

Opening the homepage sets 1 cookie (measured from a US location before any click).

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 1 host run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.