What are Progressive Web Apps? (PWA)

Pinterest, Alibaba, Twitter (now X) and Starbucks each rebuilt part of their mobile web presence as a progressive web app (PWA), and their results are among the best-known PWA case studies.

Pinterest saw a 60% increase in core engagements after rebuilding its mobile web as a PWA. Alibaba recorded a 76% increase in total conversions across all browsers after the same move. Both case studies date from 2016–2017.

PWAs are not only for companies at that scale. This guide explains what a progressive web app is, how it compares with a native app and when it makes business sense.

What are progressive web apps?

A progressive web app (PWA) is a web application built with standard browser technologies (HTML, CSS, and JavaScript) that behaves like a native mobile app. It loads in any browser, can work without an internet connection, and can be installed directly from a website to a device’s home screen, without going through an app store.

The term was coined in June 2015 by Alex Russell, a Chrome engineer at Google, and designer Frances Berriman. At the heart of the technology sits a component called a service worker: a JavaScript file that runs in the background, intercepts network requests, and serves cached content when connectivity drops. Service workers also power push notifications, which can arrive when the app is not open.

The result is a single codebase that works across devices, updates automatically and does not need an app store.

For businesses in the middle of a digital transformation, PWAs combine useful properties: search engines index them like websites, they respond like native apps, and one codebase costs less than separate iOS and Android apps.

What are the features of a progressive web app?

Eight capabilities make a web app progressive.

Progressive enhancement

A PWA works in any modern browser, on old devices as well as new ones, and adds features as the browser supports them instead of blocking access. Users on budget phones or unstable connections still get a working product.

Offline and low-connectivity support

Service workers cache resources and data on the user’s device, so the app keeps running when the network drops. A customer halfway through checkout can continue once the connection returns instead of finding an empty basket. For e-commerce and booking flows, this matters.

App-like navigation and interface

An installed PWA opens without the browser’s address bar and toolbars, with smooth transitions and the usual gestures, so it feels like an installed app. This level of UI/UX design quality used to require a dedicated native build.

Cross-device responsiveness

One codebase adapts to every screen size, from a small Android phone to a desktop monitor, with no separate mobile site. That matters when users switch between a laptop and a phone during the same task.

Instant installation

Instead of sending users to an app store, a PWA is installed from the browser with “Add to Home Screen”, and its icon appears on the device like any other app.

Automatic updates

The service worker update cycle installs new versions without user action, so users are not left on outdated versions, a common problem with native apps.

Push notifications

Push messages can reach users when the PWA is not open. They work on Android; on iOS, only for PWAs added to the home screen. This gives a re-engagement channel comparable to native apps, without the app store.

Search engine visibility

PWAs have standard URLs, so search engines can crawl their pages like any website. Native app content sits inside app stores, where Google and Bing cannot index it. For reliable indexing, a PWA’s pages should be server-side rendered (see below).

PWA vs native app: what actually changes?

The main differences are in distribution, cost and hardware access:

Two native codebases mean two development teams, two review cycles, two support queues and two sets of platform fees. A PWA replaces them with one codebase and no app store review. For mobile application development projects where speed to market matters, that is a real difference.

The cases where native still wins are narrow: deep hardware integration (ARKit, NFC chips, Bluetooth peripherals), or where an app store listing is itself part of the acquisition strategy.

What are the business benefits of a PWA?

The business case usually rests on six benefits.

1. Lower development and maintenance costs

Building one PWA instead of two native apps means one codebase, one design system and one deployment pipeline, which lowers both the initial build cost and the cost of running it. Teams managing custom software no longer maintain iOS and Android versions separately, which reduces IT support and maintenance work.

2. Shorter time to market

A PWA built on React or Vue goes through one build and no app store review, so it usually reaches production sooner than a comparable native build with separate iOS and Android review cycles. That matters for teams working to an MVP development timeline.

3. Higher mobile conversion rates

Mobile now accounts for about half of global web traffic, but mobile conversion rates still lag behind desktop. A PWA removes several steps: no app store redirect, no download wait, no installation before a user can engage. Alibaba’s 76% conversion increase across browsers after upgrading to a PWA is often cited. Users who added the site to their home screen re-engaged 4 times more often than other mobile visitors.

4. Better engagement and lower bounce rate

Pages that take longer than 3 seconds to load lose a significant share of visitors before they have seen anything. PWAs serve cached content quickly on repeat visits. Twitter Lite saw a 20% decrease in bounce rate and a 65% increase in pages per session after switching, with 75% more tweets sent. Push notifications bring users back without an app store.

5. Reduced customer acquisition cost

Every extra step between a user’s first search and their first conversion is a potential drop-off. An app store install adds several: leave the browser, find the listing, download, grant permissions, then resume. A PWA skips them. Starbucks doubled its daily active web users after launching a PWA weighing just 233KB, against 148MB for its iOS app, while keeping full ordering capability and offline support intact.

6. Headless commerce and backend flexibility

PWAs fit headless commerce architectures, where frontend and backend are decoupled. Marketing teams can change product pages and checkout flows without waiting for backend releases, a common pattern in business process automation for retail and e-commerce. Frontend development and backend development teams work in parallel rather than in sequence, which shortens release cycles.

Are progressive web apps good for SEO?

Yes, if they are built correctly.

Native app content is invisible to search engines because it sits inside app stores. A PWA has standard URLs, and Google indexes it like any other website. Compared with a native-only strategy, that is a clear advantage.

PWAs also tend to do well on the page experience signals Google uses. Service workers serve cached content quickly on repeat visits, which helps Core Web Vitals, particularly Largest Contentful Paint. Since 12 March 2024, Interaction to Next Paint (INP) has replaced First Input Delay as the Core Web Vitals responsiveness metric.

Server-side rendering matters too. When a PWA serves pre-rendered HTML instead of building the page with client-side JavaScript, crawlers get the complete content on the first request. Without it, indexing of JavaScript-rendered pages is not guaranteed.

For software testing teams, Google Lighthouse is still a useful performance and SEO check before launch. Lighthouse 12.0 (2024) removed its PWA category, so installability and offline behaviour have to be checked separately.

Progressive web app examples: three companies that got it right

Pinterest

Pinterest’s 2017 rebuild is one of the best-documented PWA case studies. Time to Interactive fell from 23 seconds on the old mobile site to 5.6 seconds on the PWA, and First Meaningful Paint from 4.2 to 1.8 seconds. Core engagements went up 60% in year one. Pinterest published a retrospective a year later: weekly active users on mobile web had grown 103% year-over-year, session length was up 296%, and users were seeing 401% more Pins per visit. The Pinterest Engineering blog has the full breakdown.

Alibaba

Alibaba.com, the world’s largest B2B trading platform operating across more than 200 countries, upgraded to a PWA and recorded a 76% increase in total conversions across all browsers. Conversions on Alibaba correspond to direct contact between buyers and suppliers, so this is a commercial outcome. Users who added the site to their home screen re-engaged 4 times more often than other mobile visitors.

Twitter Lite

Twitter Lite went live as the global default for mobile web users in April 2017. It weighed 600KB over the wire. The native Android app required 23.5MB. Google’s web dev team documented the results: 65% increase in pages per session, 75% more tweets sent, 20% decrease in bounce rate. The target was low-cost Android devices in growth markets.

In all three cases, removing friction from the mobile experience increased engagement.

What makes a good progressive web app?

Four components define the technical minimum. Since version 12.0 (2024), Google Lighthouse no longer has a PWA category, so check them directly.

Web app manifest

This is a JSON file that tells the browser how to present the installed app: its name, icon, launch URL, display mode (full-screen, standalone, or browser), and theme colour. Without a valid manifest, the browser will not offer the Add to Home Screen prompt at all. The W3C Web App Manifest specification is the authoritative reference.

Service worker

A separate JavaScript thread that intercepts network requests and serves cached responses when the network is unavailable. It is also the mechanism behind background sync and push notifications. The MDN Web Docs service worker documentation covers the full lifecycle: installation, activation, and the update process.

HTTPS

Service workers do not register on non-HTTPS origins. This is a hard constraint in the specification, not a recommendation. HTTPS is also a Google ranking signal and a basic trust signal for users. For teams thinking through cloud data security, it is the minimum.

App icon

The icon that appears on the home screen after installation. Standard sizes are 512×512 pixels in PNG, with a 192×192 variant for Android. It is the first thing a returning user sees, so treat it as a brand asset.

What are progressive web apps used for?

Reducing drop-off in multi-step flows

Every step in a checkout funnel, booking form or onboarding sequence loses some users, and funnel reports in any analytics platform show where. A PWA can reduce the loss with one-tap sign-in, saved payment details and autofill, without a native app install.

This matters particularly for fintech and financial services products, where friction at the point of commitment has an outsized effect on conversion.

Serving mobile-first audiences

According to StatCounter, mobile and desktop each account for about half of global web traffic (49.36% and 49.11% in August 2026). Native apps demand storage space, battery life and a reliable connection just to download. A PWA offers a similar experience with far less storage and data.

This matters most in markets where low-cost Android devices are the main way people go online, which is why Twitter built Twitter Lite for its growth markets. For logistics and travel and hospitality businesses whose teams move in and out of connectivity during the day, offline support is a practical requirement. A web application for mobile-first users should plan for it from the start.

Keeping users engaged after the session ends

Push notifications from a PWA appear on the lock screen and can be personalised by behaviour. On desktop, the browser has to be running in the background; on iOS, notifications work only for web apps added to the home screen. For hotel booking and travel platforms, ticket services and subscription businesses, this is a useful re-engagement channel that needs no native app install.

Key takeaways

A progressive web app removes much of the friction of native apps while giving users a similar experience.

The main arguments are lower development costs, stronger mobile engagement and a faster path to market. The best-known case studies, from Pinterest, Alibaba, Twitter and Starbucks, date from 2016–2017.

A PWA fits when most of your traffic is mobile web and you do not need deep hardware access; otherwise, build native.

To check whether a PWA is right for your product, talk to our engineers.