Lighthouse Desktop

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

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

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

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

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

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

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.

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.

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

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

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.

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

Keep the server response time for the main document short because all other requests depend on it. Learn more about the Time to First Byte metric.

Each ARIA `role` supports a specific subset of `aria-*` attributes. Mismatching these invalidates the `aria-*` attributes. Learn how to match ARIA attributes to their roles.

Some ARIA parent roles must contain specific child roles to perform their intended accessibility functions. Learn more about roles and required children elements.

Focusable descendents within an `[aria-hidden="true"]` element prevent those interactive elements from being available to users of assistive technologies like screen readers. Learn how `aria-hidden` affects focusable elements.

When an input field doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. Learn more about input field labels.

When a toggle field doesn't have an accessible name, screen readers announce it with a generic name, making it unusable for users who rely on screen readers. Learn more about toggle fields.

When a button doesn't have an accessible name, screen readers announce it as "button", making it unusable for users who rely on screen readers. Learn how to make buttons more accessible.

Link text (and alternate text for images, when used as links) that is discernible, unique, and focusable improves the navigation experience for screen reader users. Learn how to make links accessible.

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

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.

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

Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. Learn more about this errors in console diagnostic audit

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