merus.nl website review

Web fonts hide text while they load. Setting font-display: swap shows text immediately (about 1.5 s).

8 files block the first paint until they finish downloading. Deferring or inlining them could save about 1.4 s.

Your mobile performance score is 68. Pages that score under 90 lose visitors before the first paint.

4 images could be 227 KiB smaller with modern formats (WebP or AVIF) and sizes that fit a phone screen. Google estimates it would make the page about 650 ms faster on a phone.

About 123 KiB of CSS is downloaded but never applied on this page. Google estimates it would make the page about 600 ms faster on a phone.

7 files are served with short cache lifetimes, so returning visitors download them again (7 KiB).

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

1 third-party service load with your homepage (Optanon), adding 8 KiB and 0 ms of main-thread time.

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.

For real visitors the layout shifts by 0.80 (75th percentile). Good is under 0.1.

Your largest element takes 5.1 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the image.

Real visitors wait 3.7 s for the largest content to appear (75th percentile). Good is under 2.5 s.

Real visitors see the first content after 2.6 s (75th percentile). Good is under 1.8 s.

Real visitors wait 893 ms for your server to start answering (75th percentile). Good is under 800 ms.

The layout shifts by 0.187 while loading, so content jumps under the reader's thumb. Good is under 0.1.

The page becomes fully interactive after 5.3 s. Good is under 3.8 s.

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

Visually, the page fills in at 3.9 s (Speed Index). Good is under 3.4 s.

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

Over the last 25 four-week periods to 2026-10-24, real Chrome visitors' tap response (inp) went from 132 ms to 125 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 3.9 s to 3.8 s at the 75th percentile (Chrome UX Report (opens in a new tab) history).

1 image is downloaded at several times the size a phone draws it, for example MCXJCFOODFORFVLF6BGITGZKN2A4 at 1,080 px wide, shown at 340 px. Resized copies would save about 10 KiB.

By the Sustainable Web Design model, a visit to your homepage emits about 0.54 g of CO₂e: 64.2 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

Images must have alternative text: 8 elements on the page fail this check, rated critical by axe-core.

Heading levels should only increase by one: 2 elements on the page fail this check, rated moderate by axe-core.

All page content should be contained by landmarks: 1 element on the page fails this check, rated moderate by axe-core.

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

No meta description, so Google writes its own snippet from whatever text it finds.

There is no <h1>, so neither visitors nor Google get a clear main headline.

Your title is only 17 characters: “Welcome to Genmab”. Between 30 and 65 characters leaves room to say what you do and for whom.

No structured data (JSON-LD), so Google can't show rich results such as your logo, ratings or FAQs.

No canonical URL, so duplicate versions of the homepage (with or without www, with tracking parameters) can split ranking signals.

No Open Graph image (also missing: og:title, og:description), so links shared on LinkedIn, Slack or Facebook show no preview picture.

The homepage links to only 0 pages on your own site, so visitors and crawlers find few routes into the rest of it.

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

2 links have no real href, so search engines can't follow them.

No twitter:card tag. X falls back to Open Graph, which is incomplete here.

A phone browser shows 444 words, but the HTML your server sends has only 0. GPTBot, ClaudeBot and PerplexityBot read that HTML without running JavaScript, so they see an almost empty page. Server-side rendering or pre-rendering fixes it.

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.genmab.com/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.

3 of 13 tappable elements near the top of the page are smaller than 24 px, hard to hit with a thumb.

2 errors were logged to the browser console while the page loaded, for example “Loading the font 'https://navy-ss.github.io/FFMetaProBook/FFMetaProBook.woff' violates the following Content Security P…”.

Chrome logged issues while loading the page (“Content security policy”).

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.

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

There is no form on the homepage, so every lead has to click through to another page first.

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 444 words of visible text.

Before a visitor clicks anything, the page loads Google Tag Manager (measured from a US location before any click). A consent tool (OneTrust) is installed; check it blocks these until visitors agree where the law requires it.

Opening the homepage sets 2 cookies (measured from a US location before any click).

Loading the homepage contacts 5 hosts run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.