Chromium Blog

In practice, progressive web apps have three main aspects that separate them from traditional websites: reliability, performance, and engagement.

Reliability

Every web app should load quickly, regardless of whether a user is connected to fast Wi-Fi, a 2G cell network, or no connection at all. We envision service workers as the ideal way for developers to build web apps that are resilient despite changing and unreliable networks. We've released two libraries to help take the work out of writing your own service worker: sw-precache and sw-toolbox for your App Shell and dynamic content, respectively. Once your implementation is up and running, you can easily test it on different network connections using Chrome DevTools and WebPageTest. Service workers are already seeing great adoption by developers: there are currently 2.2 billion page loads a day using service workers, not counting its use in the New Tab page in Chrome.

Performance

The RAIL performance model helps you figure out what a user expects from each interaction with your site or app, breaking down performance into four key goals: 

• Responses (tap to response) should be less than 100ms 
• Animations (scrolling, gestures, and transitions) should run at 60 frames per second
• Idle time should be used to opportunistically schedule non-essential work in 50ms chunks
• Loading should be finished in under 1 second

In practice, we've found improving even just one area of RAIL performance can make a dramatic difference on the user experience. For example, a one second difference in loading time can have as much as an 11% impact on overall page views and a 16% impact on customer satisfaction.

Engagement

Traditionally, users have had a hard time re-engaging with sites on the web. Push notifications enable you to build experiences that users can engage with "outside of the tab"--they don’t need to have the browser open, or even be actively using your web app, in order to engage with your experience. Best of all, these notifications appear just like other app notifications. Currently we’re seeing over 350 million push notifications sent every day in Chrome, and it’s growing quickly. Beyond the Rack has found that users arriving to their site by push notifications browse 72% longer than average users and spend 26% more.

Tools for Success

Finally, Google is committed to making web developers successful. As our generalized library for building components on the web, Polymer is also deeply focused on helping developers achieve RAIL. Since its 1.0 release at Google I/O earlier this year, it has grown to be used on over 1 million web pages, including more than 300 projects within Google. Polymer 1.0 was 3 to 4 times faster than the previous 0.5 version, and the latest 1.2 release is even 20% faster than that. To get started with this modern way of thinking about web development, take a quick tour of Polymer, watch the Polymer Summit talks, check out the Polymer codelabs, or try the Polymer Starter Kit.

We already have great resources like Web Fundamentals that we continue to expand and improve.  We’re also committed to documenting each new feature we ship on the Mozilla Developer Network. In the past year alone, we’ve made 2,800 individual edits to MDN and created 212 new pages. To further our commitment to educating web developers, we’ve partnered with Udacity to offer a senior web nanodegree, an education credential focused on modern web technologies and techniques like service workers, Promises, HTTP/2 and more. 

For all the details on Chrome Dev Summit 2015, you can watch full session videos, which we will continue to upload as they’re ready. Thanks for coming, thanks for watching, and most of all, thank you for developing for the web!