Lighthouse Desktop

· 0 checks — Desktop 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.

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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.

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
fourmilab.ch/images/icons/brave_search_64.png	0.0 ms	3.8 KiB
fourmilab.ch/images/logo/swlogo.png	0.0 ms	2.5 KiB
fourmilab.ch/images/buttons/chrome_home.gif	0.0 ms	1.6 KiB
fourmilab.ch/images/buttons/chrome_about.gif	0.0 ms	1.6 KiB
fourmilab.ch/images/buttons/chrome_new.gif	0.0 ms	1.5 KiB
fourmilab.ch/images/buttons/chrome_find.gif	0.0 ms	1.5 KiB
fourmilab.ch/nav/topics/nav.css	0.0 ms	978 B
fourmilab.ch/images/bullets/ball_blue_white.gif	0.0 ms	868 B
fourmilab.ch/images/bullets/ball_orange_white.gif	0.0 ms	863 B
fourmilab.ch/nav/topics/nav.css	0.0 ms	0 B
fourmilab.ch/nav/topics/nav.css	0.0 ms	0 B

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Transfer Size
fourmilab.ch/nav/topics/nav.css	978 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.

Redirects introduce additional delays before the page can be loaded. Learn how to avoid page redirects.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Diagnostics

Minifying CSS files can reduce network payload sizes. Learn how to minify CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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.

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.

Lists the longest tasks on the main thread, useful for identifying worst contributors to input delay. Learn how to avoid long main-thread tasks

Why this matters

Performance issues directly impact user engagement and conversion rates.

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

●Improve image delivery

●Modern HTTP

●Network dependency tree

●Optimize viewport for mobile

●Avoids enormous network payloads Total size was 22 KiB

●JavaScript execution time 0.0 s

●Minimizes main-thread work 0.1 s

●Image elements have explicit `width` and `height`

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 30 ms

●Server Backend Latencies 0 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 30 ms

○INP breakdown

○LCP breakdown

○LCP request discovery

○User Timing marks and measures

○Avoid non-composited animations

○Avoid large layout shifts

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.

Names and labels

Screen reader users rely on frame titles to describe the contents of frames. Learn more about frame titles.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
frameset > frame `frameset > frame`
frameset > frame `frameset > frame`

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Best practices

One main landmark helps screen reader users navigate a web page. Learn more about landmarks.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html `html`

These items highlight common accessibility best practices.

○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

●Document has a `<title>` element

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

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

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

○`[accesskey]` values are unique

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

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

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

○Deprecated ARIA roles were not used

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

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

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

○ARIA input fields have accessible names

○ARIA `meter` elements have accessible names

○ARIA `progressbar` elements have accessible names

○Elements use only permitted ARIA attributes

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

○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

○`[role]` values are valid

○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

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

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

○Buttons have an accessible name

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

○Background and foreground colors have a sufficient contrast ratio

○`<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

○Heading elements appear in a sequentially-descending order

○Image elements have `[alt]` attributes

○Input buttons have discernible text.

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

○Form elements have associated labels

○Links are distinguishable without relying on color.

○Links have a discernible name

○Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).

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

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

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

○`<object>` elements have alternate text

○Select elements have associated label elements.

○Skip links are focusable.

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

○Touch targets have sufficient size and spacing.

○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.

○`[lang]` attributes have a valid value

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

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

○All heading elements contain content.

○Uses ARIA roles only on compatible elements

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

○Identical links have the same purpose.

○Elements with visible text labels have matching accessible names.

○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.

Best Practices

Browser Compatibility

Specifying a doctype prevents the browser from switching to quirks-mode. Learn more about the doctype declaration.

Why this matters

Performance issues directly impact user engagement and conversion rates.

●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

●Properly defines charset

●No browser errors logged to the console

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

●Ensure CSP is effective against XSS attacks

●Use a strong HSTS policy

●Ensure proper origin isolation with COOP

●Mitigate clickjacking with XFO or CSP

●Mitigate DOM-based XSS with Trusted Types

●Page has valid source maps

○Redirects HTTP traffic to HTTPS

○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

Meta descriptions may be included in search results to concisely summarize page content. Learn more about the meta description.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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

○Structured data is valid

●Page isn’t blocked from indexing

●Document has a `<title>` element

●Page has successful HTTP status code

●Links have descriptive text

●Links are crawlable

●robots.txt is valid

●Document has a valid `hreflang`

○Image elements have `[alt]` attributes

○Document has a valid `rel=canonical`