sciencealert.com website review

A phone's processor spends 10.4 s on main-thread work while loading, 4.7 s of it running JavaScript. Above 2 s, taps and scrolls feel sluggish.

8 third-party services load with your homepage (Rubicon Project, Taboola and Clarity and others), adding 3.2 MB and 2.3 s of main-thread time.

220 files are served with short cache lifetimes, so returning visitors download them again (1.1 MB).

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

About 990 KiB of JavaScript is downloaded but never used on this page.

Rubicon Project costs a phone 769 ms of main-thread work and 205 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.

13 images could be 430 KiB smaller with modern formats (WebP or AVIF) and sizes that fit a phone screen. Google estimates it would make the page about 300 ms faster on a phone.

Taboola costs a phone 449 ms of main-thread work and 2.0 MB 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.

20 long tasks block the main thread while loading, the longest for 526 ms. During a long task the page ignores taps.

Clarity costs a phone 287 ms of main-thread work and 27 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.

Google Tag Manager costs a phone 234 ms of main-thread work and 520 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.

futurecdn.net costs a phone 170 ms of main-thread work and 355 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.

Polyfills for old browsers add 77 KiB JavaScript that modern phones do not need.

About 40 KiB of CSS is downloaded but never applied on this page.

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

2 KiB could be saved by minifying CSS.

The page becomes fully interactive after 47.1 s. Good is under 3.8 s.

Visually, the page fills in at 11.8 s (Speed Index). Good is under 3.4 s.

Scripts block taps and scrolling for 1.3 s 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.

Your largest element takes 2.6 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the image “Strength training”.

Over the last 25 four-week periods to 2026-10-03, real Chrome visitors' largest content (lcp) went from 0.9 s to 1.1 s at the 75th percentile (Chrome UX Report (opens in a new tab) history).

Your homepage downloads 5.8 MB in 1,452 requests on a phone: scripts 3.0 MB (104), media 1.3 MB (1) and images 744 KiB (496). Under 2 MB keeps phones on slow connections fast.

By the Sustainable Web Design model, a visit to your homepage emits about 1.65 g of CO₂e: 197.9 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

<svg> elements with an img or image role must have alternative text: 4 elements on the page fail this check, rated serious by axe-core.

Page should contain a level-one heading: 1 element on the page fails this check, rated moderate by axe-core.

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

5 form fields have no label, so screen readers announce an empty box and autofill guesses.

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

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

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

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

The homepage links to 92 pages on sciencealert.com and 3 external pages.

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.

/feed has no <title>, so Google invents the link text in results.

/this-week-in-science, /about-sciencealert, /our-team, /feed, /contact-us and /privacy-policy and 2 others have no meta description, so Google writes the search snippet from whatever text it finds.

/feed and /privacy-policy have no <h1> headline, so visitors and search engines get no clear main topic.

/privacy-policy has under 150 words in the HTML. Thin pages rarely rank; if the text loads with JavaScript, crawlers that don't run it see even less.

We fetched 15 pages linked from your homepage (of 43 found) and read each the way a search engine does.

24 third-party cookies are set on load; browsers are restricting these, so whatever relies on them breaks.

12 of 41 tappable elements near the top of the page are smaller than 24 px, hard to hit with a thumb.

The page uses 1 deprecated browser API that will stop working in future browsers (“Unload event listeners are deprecated and will be removed.”).

3 errors were logged to the browser console while the page loaded, for example “Access to XMLHttpRequest at 'https://www.google.com/cse/static/element/3735a6ee3000c0cb/default_v6+en.css' from origin …”.

Chrome logged issues while loading the page (“Cookie”).

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

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.

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 302 words of visible text.

Before a visitor clicks anything, the page loads Comscore, Criteo, Google Ads, Google Analytics and Google Tag Manager and 3 mores (measured from a US location before any click). No consent tool was detected. Visitors from the EU, UK and several US states must be asked first.

Opening the homepage sets 10 cookies, 1 of them by other companies (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 31 hosts run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.