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.

100

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
[DDJ's zlib image] `body > p > img`	zlib.net/images/zlib_ddj.png	16.8 KiB	12.1 KiB
zlib `body > h1 > img`	zlib.net/images/zlib3d-b1.png	20.8 KiB	8.6 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-1-IMG

nodeLabel: zlib

path: 1,HTML,1,BODY,0,H1,0,IMG

selector: body > h1 > img

snippet: <img width="369" height="204" align="middle" src="images/zlib3d-b1.png" alt="zlib">

HTTP/2 and HTTP/3 offer many benefits over HTTP/1.1, such as multiplexing. Learn more about using modern HTTP.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Protocol
zlib.net/	http/1.1
zlib.net/images/zlib3d-b1.png	http/1.1
zlib.net/images/zlib_ddj.png	http/1.1
zlib.net/zlib-email.png	http/1.1
zlib.net/images/li_blue.png	http/1.1
zlib.net/images/li_green.png	http/1.1
zlib.net/images/li_red.png	http/1.1
zlib.net/images/li_yellow.png	http/1.1
zlib.net/madler-email.png	http/1.1
zlib.net/favicon.ico	http/1.1

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
zlib.net/images/zlib3d-b1.png	604800.0 s	21.4 KiB
zlib.net/images/zlib_ddj.png	604800.0 s	17.3 KiB
zlib.net/madler-email.png	604800.0 s	1.9 KiB
zlib.net/zlib-email.png	604800.0 s	1.4 KiB
zlib.net/images/li_green.png	604800.0 s	819 B
zlib.net/images/li_blue.png	604800.0 s	816 B
zlib.net/images/li_red.png	604800.0 s	816 B
zlib.net/images/li_yellow.png	604800.0 s	812 B

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

Diagnostics

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
Mark's email address `body > i > img`	zlib.net/madler-email.png
zlib email address `body > p > img`	zlib.net/zlib-email.png
zlib email address `dd > dl > dd > img`	zlib.net/zlib-email.png
zlib email address `body > i > img`	zlib.net/zlib-email.png

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

●Network dependency tree

●Render blocking requests

●Optimize viewport for mobile

●Time to Interactive 0.3 s

●Max Potential First Input Delay 20 ms

●Minify CSS

●Minify JavaScript

●Reduce unused CSS

●Reduce unused JavaScript

●Avoids enormous network payloads Total size was 59 KiB

●Minimizes main-thread work 0.1 s

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 160 ms

●Server Backend Latencies 10 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 170 ms

○INP breakdown

○User Timing marks and measures

○JavaScript execution time

○Avoid long main-thread tasks

○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.

Tables and lists

When definition lists are not properly marked up, screen readers may produce confusing or inaccurate output. Learn how to structure definition lists correctly.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Canonical URL: https://zlib.net/ (US) `body > dl`
zlib source code, version 1.3.2, tar.gz format (1468K, SHA-256 hash bb329a0a2c… `body > dl`
US (zlib.net) (GPG signature) `body > dl > dd > dl`
US (zlib.net) (GPG signature) `body > dl > dd > dl`
US (zlib.net) (GPG signature) `body > dl > dd > dl`
https://zlib.net/current/zlib.tar.gz `body > dl`
zlib Frequently Asked Questions Zlib-announce mailing list New versions of zl… `body > dl`
New versions of zlib are announced on this list. `body > dl > dd > dl`
Please do not send questions or comments about zlib to this mailing list. Send … `body > dl > dd > dl`
Ross Williams' classic "A Painless Guide to CRC Error Detection Algorithms" C… `body > dl`
Code to read a zip file as a stream and extract its contents. sunzip.c will re… `body > dl`
zlib for Linux, both shared and static plus headers (RPM format, many architec… `body > dl`
(unsupported VB5 binary also available) `body > dl > dd > dl`
(includes compiled object files and corresponding C++ Builder 5 project files) `body > dl > dd > dl`
(not tested by us, but looks like a good alternative to java.util.zip) `body > dl > dd > dl`
(see also Info-ZIP's UnZip, which optionally can be compiled with zlib) `body > dl > dd > dl`
(not tested by us, but looks like a good alternative if you need more speed and… `body > dl > dd > dl`
(not tested by us, but looks like an even better alternative if you need more s… `body > dl > dd > dl`
(not tested by us, but appears to be a better alternative to zlib in both dimen… `body > dl > dd > dl`
(not tested by us, but looks like a good alternative if you need more compressi… `body > dl > dd > dl`

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

Navigation

Properly ordered headings that do not skip levels convey the semantic structure of the page, making it easier to navigate and understand when using assistive technologies. Learn more about heading order.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
A Massively Spiffy Yet Delicately Unobtrusive Compression Library (Also Free, N… `body > h3`

These are opportunities to improve keyboard navigation in your application.

Internationalization and localization

If a page doesn't specify a `lang` attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more about the `lang` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html `html`

These are opportunities to improve the interpretation of your content by users in different locales.

Best practices

Touch targets with sufficient size and spacing help users who may have difficulty targeting small controls to activate the targets. Learn more about touch targets.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
zlib Frequently Asked Questions `body > dl > dd > a`
Zlib-announce mailing list `body > dl > dd > a`
zlib Manual `body > dl > dd > a`
zlib Usage Example `body > dl > dd > a`
zlib Technical Details `body > dl > dd > a`
RFC 1950 ZLIB Compressed Data Format Specification version 3.3 `dd > ul > li > a`
RFC 1951 DEFLATE Compressed Data Format Specification version 1.3 `dd > ul > li > a`
RFC 1952 GZIP file format specification version 4.3 `dd > ul > li > a`
zlib's Deflate Algorithm `body > dl > dd > a`
zlib's deflate flush modes `body > dl > dd > a`
zlib License `body > dl > dd > a`
All released versions of zlib `body > dl > dd > a`
zlib on github `body > dl > dd > a`
Ross Williams' classic "A Painless Guide to CRC Error Detection Algorithms" `body > dl > dd > a`
zlib for Palm Pilot `body > dl > dd > a`
zlib for Newton OS `body > dl > dd > a`
zlib for Windows CE `body > dl > dd > a`
zlib for .NET in C# `body > dl > dd > a`
zlib DLL wrapper for .NET in C# `body > dl > dd > a`
Zip for .NET `body > dl > dd > a`
zlib Haskell interface `body > dl > dd > a`
zlib reimplementation in pure Java `body > dl > dd > a`
zlib technical issues, including spec errors `body > dl > dd > a`
Zip Files: History, Explanation and Implementation `body > dl > dd > a`
zlib information in Japanese `body > dl > dd > a`
zlib information in Russian `body > dl > dd > a`
Info-ZIP Home Page `body > dl > dd > a`
gzip Home Page `body > dl > dd > a`
pigz (parallel gzip) Home Page `body > dl > dd > a`
DataCompression.info `body > dl > dd > a`

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

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

●Image elements have `[alt]` attributes

●Background and foreground colors have a sufficient contrast ratio

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

●Document has a `<title>` element

●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

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

●Identical links have the same purpose.

○`[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"]` 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

○ARIA IDs are unique

○No form fields have multiple labels

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

○`<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.

○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">`

○`[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

○`<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.

○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 DOM-based XSS with Trusted Types

●Page has valid source maps

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

○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

●Image elements have `[alt]` attributes

●Document has a valid `hreflang`

○Document has a valid `rel=canonical`