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

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

Consider using `<link rel=preload>` to prioritize fetching resources that are currently requested later in page load. Learn more.

Minifying JavaScript files can reduce payload sizes and script parse time. Learn more.

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.

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

Third-party code can significantly impact load performance. Limit the number of redundant third-party providers and try to load third-party code after your page has primarily finished loading. Learn more.

For users on slow connections, external scripts dynamically injected via `document.write()` can delay page load by tens of seconds. Learn more.

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

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

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

A large DOM will increase memory usage, cause longer style calculations, and produce costly layout reflows. Learn more.

Large network payloads cost users real money and are highly correlated with long load times. 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.

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

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

These DOM elements contribute most to the CLS of the page.

Consider instrumenting your app with the User Timing API to measure your app's real-world performance during key user experiences. Learn more.

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

Descriptive link text helps search engines understand your content. 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.

Deprecated APIs will eventually be removed from the browser. Learn more.

Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. 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.

A themed splash screen ensures a high-quality experience when users launch your app from their homescreens. Learn more. Failures: Manifest does not have a PNG icon of at least 512px.

Your app should display some content when JavaScript is disabled, even if it's just a warning to the user that JavaScript is required to use the app. Learn more. The page body should render some content if its scripts are not available.

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.

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.

A service worker enables your web app to be reliable in unpredictable network conditions. Learn more. The start_url did respond, but not via a service worker.

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

A fast page load over a cellular network ensures a good mobile user experience. Learn more. Your page loads too slowly and is not interactive within 10 seconds. Look at the opportunities and diagnostics in the "Performance" section to learn how to improve.

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 more.

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

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 more.

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