Lighthouse Mobile

· 0 checks — Mobile Lighthouse audit -- Performance, Accessibility, Best Practices, and SEO category breakdown.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

Detailed Report

Audit breakdown by category with detailed findings.

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Performance issues directly impact user engagement and conversion rates.

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL	Resource Size	Est Savings
section.yt-homepage-hero-refresh > div.yt-homepage-hero-refresh__video-bg-container > picture.yt-homepage-hero-refresh__video-bg > img `section.yt-homepage-hero-refresh > div.yt-homepage-hero-refresh__video-bg-container > picture.yt-homepage-hero-refresh__video-bg > img`	/static/blog_youtube/videos/bg-hero-mobile.webp?version=p...	279.3 KiB	245.1 KiB
div.youtube-specific-topic-card__multimedia > a.youtube-specific-topic-card__media-link > div.youtube-specific-topic-card__mp4-video-container > video#FeaturedArticle3498 `div.youtube-specific-topic-card__multimedia > a.youtube-specific-topic-card__media-link > div.youtube-specific-topic-card__mp4-video-container > video#FeaturedArticle3498`	/gweb-uniblog-publish-prod/original_videos/wagtailvideo-3...	58.9 KiB	48.7 KiB

Optimize LCP by making the LCP image discoverable from the HTML immediately, and avoiding lazy-loading

Why this matters

Performance issues directly impact user engagement and conversion rates.

lhId: page-0-IMG

nodeLabel: section.yt-homepage-hero-refresh > div.yt-homepage-hero-refresh__video-bg-container > picture.yt-homepage-hero-refresh__video-bg > img

path: 1,HTML,1,BODY,8,MAIN,1,SECTION,1,DIV,0,PICTURE,3,IMG

selector: section.yt-homepage-hero-refresh > div.yt-homepage-hero-refresh__video-bg-container > picture.yt-homepage-hero-refresh__video-bg > img

snippet: <img type="image/webp" src="https://blog.youtube/static/blog_youtube/videos/bg-hero-mobile.webp?versio…" alt="">

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Request	Cache TTL	Transfer Size
i.ytimg.com/vi_webp/m3kR2KK8TEs/maxresdefault.webp	7200.0 s	61.5 KiB
/a?v=3&t=l&pid=87208056&rv=64k0&tag_exp=0~115616985~11593...	0.0 ms	11 B

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Time to Interactive is the amount of time it takes for the page to become fully interactive. Learn more about the Time to Interactive metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

TTI

The maximum potential First Input Delay that your users could experience is the duration of the longest task. Learn more about the Maximum Potential First Input Delay metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Diagnostics

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity. Learn how to reduce unused CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 150 ms 33.2 KiB

URL	Transfer Size	Est Savings
blog.youtube/static/youtube/css/homepage/index.min.css?version=pr20260415-1638	42.0 KiB	33.2 KiB

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 600 ms 116.8 KiB

URL	Transfer Size	Est Savings
www.googletagmanager.com/gtag/js?id=G-8LV49FDYJ3&cx=c&gtm=4e64k0	144.0 KiB	61.0 KiB
www.googletagmanager.com/gtm.js?id=GTM-W8LC8VL	127.4 KiB	55.8 KiB

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to minimize main-thread work

Why this matters

Performance issues directly impact user engagement and conversion rates.

Category	Time Spent
Other	809 ms
Script Evaluation	700 ms
Style & Layout	492 ms
Rendering	371 ms
Script Parsing & Compilation	95 ms
Parse HTML & CSS	37 ms
Garbage Collection	22 ms

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL
youtube red carpet creators `div.youtube-specific-topic-card__multimedia > a.youtube-specific-topic-card__media-link > figure.youtube-specific-topic-card__image-container > img.youtube-specific-topic-card__image`	/gweb-uniblog-publish-prod/images/Image_20251113_201733.m...
A screenshot of the Delta Studio in-flight entertainment system showing the "Se… `div.youtube-specific-topic-card__multimedia > a.youtube-specific-topic-card__media-link > figure.youtube-specific-topic-card__image-container > img.youtube-specific-topic-card__image`
christian oestlien and michelle khare `div.youtube-specific-topic-card__multimedia > a.youtube-specific-topic-card__media-link > figure.youtube-specific-topic-card__image-container > img.youtube-specific-topic-card__image`

More information about the performance of your application. These numbers don't directly affect the Performance score.

●Layout shift culprits

●Document request latency

●Optimize DOM size

●Font display

●Forced reflow

●LCP breakdown

●Modern HTTP

●Network dependency tree

●Render blocking requests

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●Avoids enormous network payloads Total size was 1,291 KiB

●User Timing marks and measures 169 user timings

●JavaScript execution time 0.7 s

●Avoid long main-thread tasks 5 long tasks found

●Avoid non-composited animations 12 animated elements found

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 30 ms

●Server Backend Latencies 40 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Avoid multiple page redirects

●Initial server response time was short Root document took 190 ms

●Avoid large layout shifts 2 layout shifts found

○INP breakdown

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

Contrast

Low-contrast text is difficult or impossible for many users to read. Learn how to provide sufficient color contrast.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
WORK DIARIES `div.youtube-discover-more__wrapper > ul.youtube-discover-more__tags > li.youtube-discover-more__tag > a.youtube-discover-more__link`

Low-contrast text is difficult or impossible for many users to read. Link text that is discernible improves the experience for users with low vision. Learn how to make links distinguishable.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Learn more `body.template-youtube-homepage > div#glue-cookie-notification-bar-1 > p.glue-cookie-notification-bar__text > a.glue-cookie-notification-bar__more`

These are opportunities to improve the legibility of your content.

Tables and lists

Screen readers have a specific way of announcing lists. Ensuring proper list structure aids screen reader output. Learn more about proper list structure.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
NEWS AND EVENTS EXPANDING LIKENESS DETECTION TO THE ENTERTAINMENT INDUSTRY BY … `section.yt-carousel-short-posts > div.grid > div.yt-carousel-short-posts__wrapper > ul.yt-carousel-short-posts__carousel`

These are opportunities to improve the experience of reading tabular or list data using assistive technology, like a screen reader.

○Interactive controls are keyboard focusable

○Interactive elements indicate their purpose and state

○The page has a logical tab order

○Visual order on the page follows DOM order

○User focus is not accidentally trapped in a region

○The user's focus is directed to new content added to the page

○HTML5 landmark elements are used to improve navigation

○Offscreen content is hidden from assistive technology

○Custom controls have associated labels

○Custom controls have ARIA roles

●`[aria-*]` attributes match their roles

●`[aria-hidden="true"]` is not present on the document `<body>`

●`[role]`s have all required `[aria-*]` attributes

●`[role]` values are valid

●`[aria-*]` attributes have valid values

●`[aria-*]` attributes are valid and not misspelled

●Buttons have an accessible name

●Image elements have `[alt]` attributes

●`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.

●Select elements have associated label elements.

●ARIA attributes are used as specified for the element's role

●Elements with `role="dialog"` or `role="alertdialog"` have accessible names.

●`[aria-hidden="true"]` elements do not contain focusable descendents

●Elements use only permitted ARIA attributes

●Document has a `<title>` element

●`<html>` element has a `[lang]` attribute

●`<html>` element has a valid value for its `[lang]` attribute

●Links have a discernible name

●List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements

●No element has a `[tabindex]` value greater than 0

●Touch targets have sufficient size and spacing.

●`[lang]` attributes have a valid value

●Heading elements appear in a sequentially-descending order

●Document has a main landmark.

●Deprecated ARIA roles were not used

●`<video>` elements contain a `<track>` element with `[kind="captions"]`

●Uses ARIA roles only on compatible elements

●Elements with visible text labels have matching accessible names.

○`[accesskey]` values are unique

○`button`, `link`, and `menuitem` elements have accessible names

○ARIA input fields have accessible names

○ARIA `meter` elements have accessible names

○ARIA `progressbar` elements have accessible names

○Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.

○`[role]`s are contained by their required parent element

○Elements with the `role=text` attribute do not have focusable descendents.

○ARIA toggle fields have accessible names

○ARIA `tooltip` elements have accessible names

○ARIA `treeitem` elements have accessible names

○The page contains a heading, skip link, or landmark region

○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.

○Definition list items are wrapped in `<dl>` elements

○ARIA IDs are unique

○No form fields have multiple labels

○`<frame>` or `<iframe>` elements have a title

○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.

○Input buttons have discernible text.

○`<input type="image">` elements have `[alt]` text

○Form elements have associated labels

○The document does not use `<meta http-equiv="refresh">`

○`<object>` elements have alternate text

○Skip links are focusable.

○Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.

○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.

○Tables have different content in the summary attribute and `<caption>`.

○All heading elements contain content.

○Image elements do not have `[alt]` attributes that are redundant text.

○Identical links have the same purpose.

○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.

○`<td>` elements in a large `<table>` have one or more table headers.

100

Best Practices

●Uses HTTPS

●Avoids deprecated APIs

●Avoids third-party cookies

●Allows users to paste into input fields

●Avoids requesting the geolocation permission on page load

●Avoids requesting the notification permission on page load

●Displays images with correct aspect ratio

●Serves images with appropriate resolution

●Page has the HTML doctype

●Properly defines charset

●No browser errors logged to the console

●No issues in the `Issues` panel in Chrome Devtools

●Use a strong HSTS policy

●Ensure proper origin isolation with COOP

●Mitigate clickjacking with XFO or CSP

●Page has valid source maps

○Redirects HTTP traffic to HTTPS

○Ensure CSP is effective against XSS attacks

○Mitigate DOM-based XSS with Trusted Types

○Detected JavaScript libraries

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

Content Best Practices

Descriptive link text helps search engines understand your content. Learn how to make links more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Link destination	Link Text
policies.google.com/technologies/cookies?hl=en	Learn more
blog.youtube/topic-hub/youtube-tv/	READ MORE

Format your HTML in a way that enables crawlers to better understand your app’s content.

Crawling and Indexing

Search engines may use `href` attributes on links to crawl websites. Ensure that the `href` attribute of anchor elements links to an appropriate destination, so more pages of the site can be discovered. Learn how to make links crawlable

Why this matters

Performance issues directly impact user engagement and conversion rates.

Uncrawlable Link
Newsletter subscribe `div.yt-newsletter-toast > div.yt-newsletter-toast__container > div.yt-newsletter-toast__content > a.yt-newsletter-toast--cta-sub`

To appear in search results, crawlers need access to your app.

○Structured data is valid

●Page isn’t blocked from indexing

●Document has a `<title>` element

●Document has a meta description

●Page has successful HTTP status code

●robots.txt is valid

●Image elements have `[alt]` attributes

●Document has a valid `hreflang`

●Document has a valid `rel=canonical`