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.

Layout shifts occur when elements move absent any user interaction. Investigate the causes of layout shifts, such as elements being added, removed, or their fonts changing as the page loads.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:node label:Element subItemsHeading:map[key:extra] valueType:node] map[granularity:0.001 key:score label:Layout shift score subItemsHeading:map[key:cause valueType:text] valueType:numeric]]

items: [map[node:map[type:text value:Total] score:1.421108] map[node:map[boundingRect:map[bottom:3113 height:2572 left:0 right:412 top:541 width:412] lhId:page-7-MAIN nodeLabel:The home of UK public data to inform decisions and build services Find out mor… path:1,HTML,1,BODY,4,MAIN selector:body.govuk-template__body > main#main snippet:<main id="main" class="datagovuk-main"> type:node] score:0.889877] map[node:map[boundingRect:map[bottom:3666 height:3646 left:0 right:412 top:20 width:412] lhId:page-9-BODY nodeLabel:body.govuk-template__body path:1,HTML,1,BODY selector:body.govuk-template__body snippet:<body class="govuk-template__body js-enabled govuk-frontend-supported"> type:node] score:0.531231]]

A forced reflow occurs when JavaScript queries geometric properties (such as offsetWidth) after styles have been invalidated by a change to the DOM state. This can result in poor performance. Learn more about forced reflows and possible mitigations.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]

items: [map[reflowTime:33.132 source:map[type:text value:[unattributed]]]]

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
div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image `div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image`	/find-assets/v2/collections/badge-people-ea1d57564368da33...	51.0 KiB	48.5 KiB
div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image `div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image`	/find-assets/v2/collections/badge-government-441d78215c73...	50.8 KiB	48.3 KiB
div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image `div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image`	/find-assets/v2/collections/badge-land-and-property-e6d19...	49.8 KiB	47.4 KiB
div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image `div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image`	/find-assets/v2/collections/badge-transport-0c2fc879379f0...	48.2 KiB	45.7 KiB
div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image `div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image`	/find-assets/v2/collections/badge-environment-0c106b83ab0...	44.6 KiB	42.1 KiB
div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image `div.datagovuk-home-collections > div.datagovuk-home-collections__items > div.datagovuk-home-collections__item > img.datagovuk-home-collections__item-image`	/find-assets/v2/collections/badge-business-and-economy-c2...	33.5 KiB	31.1 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-6-DIV

nodeLabel: The home of UK public data to inform decisions and build services Find out mor…

path: 1,HTML,1,BODY,4,MAIN,0,DIV,0,DIV

selector: body.govuk-template__body > main#main > div.govuk-width-container > div.datagovuk-home-hero

snippet: <div class="datagovuk-home-hero">

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.

title: Preconnected origins

value: no origins were preconnected

description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.

title: Preconnect candidates

value: No additional origins are good candidates for preconnecting

Your first network request is the most important. Reduce its latency by avoiding redirects, ensuring a fast server response, and enabling text compression.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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

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.

Estimated savings: 750 ms

URL	Time Spent
data.gov.uk/	750 ms
www.data.gov.uk/	0.0 ms

These are the largest layout shifts observed on the page. Each table item represents a single layout shift, and shows the element that shifted the most. Below each item are possible root causes that led to the layout shift. Some of these layout shifts may not be included in the CLS metric value due to windowing. Learn how to improve CLS

Why this matters

Performance issues directly impact user engagement and conversion rates.

Element	Layout shift score
The home of UK public data to inform decisions and build services Find out mor… `body.govuk-template__body > main#main`	0.890
body.govuk-template__body `body.govuk-template__body`	0.531

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.

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

Diagnostics

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: 900 ms 245.7 KiB

URL	Transfer Size	Est Savings
/find-assets/v2/application-fefafe876eb73609633cb4fe79695...	178.8 KiB	140.0 KiB
www.googletagmanager.com/gtm.js?id=GTM-5WRWCH8X&	125.5 KiB	67.3 KiB
www.data.gov.uk/javascript/govuk-frontend-6.0.0.min.js	45.8 KiB	38.4 KiB

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: 0.0 ms 13.7 KiB

URL	Transfer Size	Est Savings
/find-assets/v2/govuk-frontend-6.0.0.min-0b4f1b047b982122...	14.6 KiB	13.7 KiB

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

●Use efficient cache lifetimes

●Optimize DOM size

●Font display

●LCP breakdown

●Modern HTTP

●Render blocking requests

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●Avoids enormous network payloads Total size was 828 KiB

●JavaScript execution time 0.4 s

●Minimizes main-thread work 0.9 s

●Avoid long main-thread tasks 3 long tasks found

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

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 20 ms

●Server Backend Latencies 10 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 0 ms

○INP breakdown

○User Timing marks and measures

○Avoid non-composited animations

100

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.

○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.

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

●Elements use only permitted ARIA attributes

●Background and foreground colors have a sufficient contrast ratio

●Document has a `<title>` element

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

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

●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

●Touch targets have sufficient size and spacing.

●Heading elements appear in a sequentially-descending order

●Document has a main landmark.

●Deprecated ARIA roles were not used

○`[accesskey]` values are unique

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

○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 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

○Select elements have associated label elements.

○Skip links are focusable.

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

○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.

100

Best Practices

General

Source maps translate minified code to the original source code. This helps developers debug in production. In addition, Lighthouse is able to provide further insights. Consider deploying source maps to take advantage of these benefits. Learn more about source maps.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Map URL
/find-assets/v2/application-fefafe876eb73609633cb4fe79695...
www.data.gov.uk/javascript/govuk-frontend-6.0.0.min.js	www.data.gov.uk/javascript/govuk-frontend.min.js.map

●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

●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

●Detected JavaScript libraries

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

100

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.

○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

●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`