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Image formats like JPEG 2000, JPEG XR, and WebP often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. Learn more.

Optimized images load faster and consume less cellular data. Learn more.

Redirects introduce additional delays before the page can be loaded. Learn more.

Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. Learn more.

Remove unused JavaScript to reduce bytes consumed by network activity. Learn more.

Remove dead rules from stylesheets and defer the loading of CSS not used for above-the-fold content to reduce unnecessary bytes consumed by network activity. Learn more.

Leverage the font-display CSS feature to ensure text is user-visible while webfonts are loading. Learn more.

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

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn more

To set budgets for the quantity and size of page resources, add a budget.json file. Learn more.

This is the largest contentful element painted within the viewport. Learn More

The Critical Request Chains below show you what resources are loaded with a high priority. Consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load. Learn more.

Lists the longest tasks on the main thread, useful for identifying worst contributors to input delay. Learn more

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

Specifying a doctype prevents the browser from switching to quirks-mode. Learn more. Document must contain a doctype

Image natural dimensions should be proportional to the display size and the pixel ratio to maximize image clarity. Learn more.

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being servedover HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more.

Some third-party scripts may contain known security vulnerabilities that are easily identified and exploited by attackers. Learn more.

A service worker enables your web app to be reliable in unpredictable network conditions. Learn more. No usable web app manifest found on page.

If you're building a Progressive Web App, consider using a service worker so that your app can work offline. Learn more.

A themed splash screen ensures a high-quality experience when users launch your app from their homescreens. Learn more. Failures: No manifest was fetched.

For ideal appearance on iOS when users add a progressive web app to the home screen, define an `apple-touch-icon`. It must point to a non-transparent 192px (or 180px) square PNG. Learn More.

A maskable icon ensures that the image fills the entire shape without being letterboxed when installing the app on a device. Learn more. No manifest was fetched

The browser address bar can be themed to match your site. Learn more. Failures: No manifest was fetched, No `<meta name="theme-color">` tag found.

Browsers can proactively prompt users to add your app to their homescreen, which can lead to higher engagement. Learn more. Failures: No manifest was fetched.

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being servedover HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more.

The service worker is the technology that enables your app to use many Progressive Web App features, such as offline, add to homescreen, and push notifications. Learn more.

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

Adding ways to bypass repetitive content lets keyboard users navigate the page more efficiently. Learn more.

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.