deeplearning.ai website review

18 files are served with short cache lifetimes, so returning visitors download them again (630 KiB).

About 700 KiB of JavaScript is downloaded but never used on this page. Google estimates it would make the page about 2.4 s faster on a phone.

Your mobile performance score is 58 (desktop: 66). Pages that score under 90 lose visitors before the first paint.

8 third-party services load with your homepage (Google Tag Manager, Facebook and Hubspot and others), adding 1.5 MB and 748 ms of main-thread time.

Google Tag Manager costs a phone 350 ms of main-thread work and 696 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.

A phone's processor spends 2.7 s on main-thread work while loading, 1.6 s of it running JavaScript. Above 2 s, taps and scrolls feel sluggish.

Hubspot costs a phone 114 ms of main-thread work and 313 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 58 KiB JavaScript that modern phones do not need. Google estimates it would make the page about 150 ms faster on a phone.

3 files block the first paint until they finish downloading. Deferring or inlining them could save about 200 ms.

14 long tasks block the main thread while loading, the longest for 131 ms. During a long task the page ignores taps.

5 images could be 67 KiB smaller with modern formats (WebP or AVIF) and sizes that fit a phone screen.

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.

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 17.2 s to render on a phone. Google's threshold for “good” is 2.5 s. The largest element is the image “Andrew Ng, Founder of DeepLearning.AI”.

The page becomes fully interactive after 22.4 s. Good is under 3.8 s.

Visually, the page fills in at 6.7 s (Speed Index). Good is under 3.4 s.

Real visitors wait 336 ms for the page to respond to a tap (75th percentile). Good is under 200 ms.

Over the last 25 four-week periods to 2026-10-24, real Chrome visitors' tap response (inp) went from 204 ms to 348 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 2.0 s to 2.6 s at the 75th percentile (Chrome UX Report (opens in a new tab) history).

Real visitors see the first content after 2.0 s (75th percentile). Good is under 1.8 s.

Real visitors wait 1.1 s for your server to start answering (75th percentile). Good is under 800 ms.

Scripts block taps and scrolling for 410 ms in total while the page loads. Good is under 200 ms.

Your homepage downloads 2.9 MB in 140 requests on a phone: scripts 2.2 MB (62), images 438 KiB (31) and fonts 177 KiB (5). Under 2 MB keeps phones on slow connections fast.

By the Sustainable Web Design model, a visit to your homepage emits about 0.83 g of CO₂e: 99.6 kg a year at 10,000 visits a month. It scales with page weight, so every byte cut lowers it.

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

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

ARIA commands must have an accessible name: 1 element on the page fails this check, rated serious by axe-core.

Your meta description is 192 characters; Google truncates after about 160, so the end of your pitch is cut.

No favicon is declared in the HTML, so browser tabs and Google's mobile results may show a generic icon.

The homepage links to 56 pages on deeplearning.ai and 21 external pages.

robots.txt blocks GPTBot, ClaudeBot, Applebot-Extended and CCBot, which collect pages to train models. That's a legitimate choice and doesn't by itself stop the site appearing in AI answers, which the crawlers above handle.

/my/start-pro has no <title>, so Google invents the link text in results.

/my/start-pro has no meta description, so Google writes the search snippet from whatever text it finds.

/courses, /business, /business/plans-pricing, /business/learningtracks and /business/contact-us use the same meta description. A description written for each page earns more clicks.

/my/start-pro has no <h1> headline, so visitors and search engines get no clear main topic.

We fetched 15 pages linked from your homepage (of 25 found) and read each the way a search engine does.

4 of 14 tappable elements near the top of the page are smaller than 24 px, hard to hit with a thumb.

Large scripts ship without source maps.

1 link from your homepage to your own site is broken, for example https://www.deeplearning.ai/my/start-pro (404).

HSTS is set, but max-age is 180 days; one year is the recommended minimum.

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.

deeplearning.ai is registered until Nov 2026. Make sure auto-renew is on and the card on file is current.

deeplearning.ai's DNS answers are not signed. DNSSEC stops attackers forging them to send visitors or email elsewhere; most registrars switch it on in a click, though most sites still run without it.

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 530 words of visible text.

DMARC is set to p=none, so mail pretending to be deeplearning.ai is still delivered. Add a report address, check the reports, then move to quarantine.

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.

Before a visitor clicks anything, the page loads Google Ads, Google Analytics, Google Tag Manager, Hotjar and HubSpot and 3 mores (measured from a US location before any click). A consent tool (HubSpot cookie banner) is installed; check it blocks these until visitors agree where the law requires it.

Opening the homepage sets 15 cookies (measured from a US location before any click).

Loading the homepage contacts 36 hosts run by other companies (fonts, scripts, analytics, ads), each of which sees the visitor's IP address.