Love to use Bookmarks and want it on web? Into scrolling through Explore to see what's happening? We are testing out a new Twitter for web, which a small number of people will see today. Love it? Missing something? Reply and tell us. Don't have the new experience? Stay tuned. pic.twitter.com/w4TiRrVFHU — Twitter (@Twitter) September 6, 2018

Twitter is showing some users of its desktop website a new user interface that is designed to be faster and to feature support for the recently added bookmarks feature (supported in the iOS and Android clients but not, currently, the main website), a data-saver mode, and a night mode. These users have been selected at random and moved over to the new interface so they can test the interface and provide feedback.

The new interface isn't all that different from the old one: it's organized a little differently, with a two-column layout instead of the three columns currently used, but overall it will feel familiar to anyone who has used the microblogging platform before. What makes this move interesting isn't the specifics of the interface itself, but the technology it's built on.

The new interface isn't actually new at all. It has been available for some time now as mobile.twitter.com, Twitter's mobile-friendly Web interface. In turn, that same Web interface is used to drive the Windows 10 app, the KaiOS platform for "smart feature phones," and the recently released Twitter Lite app for Android. This is why it has the data-saver mode; it has been designed with an eye on those users who suffer from poor or expensive bandwidth or have underpowered devices.

This mobile site is perhaps one of the most prominent instances of what could be a new breed of Web application: the Progressive Web Application (PWA). PWAs are Web applications that build on certain modern browser features to provide an experience that is much more like that of a traditional application. For example, PWAs can support offline operation using service workers (a way of running JavaScript in the background that can respond to events and make network requests that degrade gracefully if the network is unavailable); they integrate with platform features such as notifications; they're also designed so that they could be pinned to app launchers and home screens and treated as if they were "real" applications rather than merely webpages.

A brief history of PWA

The PWA concept—the particular range of features and behaviors that made these apps work and feel a bit different from their traditional Web predecessors—was devised by Google in 2015. Since then, both Google and Microsoft have been promoting the concept as a way of bridging the gap between Web app and native app. Done well, PWAs offer the best parts of native applications—such as push notifications, offline operation, and icons on the home screen—with the best parts of the Web, such as always up-to-date code, a responsive design that handles a range of form factors, and the ability to share content with hyperlinks.

Twitter has been quietly developing its PWA for months. Switching some desktop users over to it is arguably the biggest, most visible use of a PWA so far.

In the longer term, wider adoption of PWA techniques means that, one day, Steve Jobs' vision for smartphone applications might truly be realized: no need for phone SDKs or new development tools and languages, but a world in which Web technology can be used to create applications that are every bit the equal of their native counterparts.

Listing image by Marie Slim / Flickr