Hello.

We rebuilt Pinterest's mobile web experience as a PWA and the results after one year have exceeded our expectations. Weekly active users on mobile web have increased 103% year-over-year, with even higher growth in Brazil (156%) and India (312%). Engagement metrics also saw incredible growth: session length (+296%), Pins seen (+401%), and Pin saves (+295%). Perhaps most importantly, logins increased by 370% and new signups by a staggering 843% year-over-year, making mobile web our top platform for new signups. We've seen 800,000 weekly users add the PWA to their homescreen in under 6 months. Beyond performance, this new platform supports right-to-left languages and night mode, making it more accessible. We're proud of this user experience and excited to continue building on this foundation.

At Google I/O 2011, we showcased a mobile web app. Many asked about its development timeline. Work began on March 3rd, with core coding starting on March 25th. While the calendar time was just over a month, the effort was spread across four engineers, each dedicating about 20% of their time to their respective UI using the FormFactorJS framework. This setup facilitated isolated development, with the flexibility to inject custom code per form factor and a common base controller in controller.js. We also developed and leveraged two frameworks, LeviRoutes and FormfactorJS, to efficiently consolidate common logic and specialize the controller according to form factors.