What are Progressive Web Apps? (PWA)

What do Pinterest, Alibaba, Twitter, and Starbucks have in common? Each rebuilt part of their mobile web presence as a progressive web app, and each recorded results that would be hard to explain to a native-app sceptic.

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. These are not edge cases. They are repeatable outcomes from a technology that most businesses have not yet taken seriously.

The reason is usually one of two things: teams do not fully understand what a progressive web app is, or they assume it is only relevant to companies at scale. Neither is true.

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 by Google engineers in 2015. 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 are also what power push notifications when the browser is closed.

What this produces is something neither a standard website nor a native app has quite managed before: a single codebase, working across every device, that updates automatically and never requires a trip to an app store.

For businesses working through a broader digital transformation, PWAs sit at a useful intersection. They are indexed by search engines like websites. They load with the responsiveness of native apps. And they cost considerably less to build than maintaining separate iOS and Android codebases, which is where the business case tends to start making itself clear.

What are the features of a progressive web app?

Eight capabilities define what makes a web app progressive rather than just fast.

Progressive enhancement

Not all users arrive on high-end hardware with a stable connection. A PWA handles that gracefully. It functions in any modern browser, on older devices as much as new ones, expanding its feature set as browser capabilities allow rather than blocking access. Budget smartphones get a working experience. That is not a given with native apps.

Offline and low-connectivity support

Service workers cache resources and data locally on the user’s device. When the network drops, the app keeps running from that cache. A customer halfway through a checkout can pick up where they left off once connectivity returns, rather than finding an empty basket and a loading spinner. For e-commerce and booking flows, this is not a nice-to-have.

App-like navigation and interface

There is no browser chrome, no visible URL bar, no feeling of “browsing.” Transitions are smooth. Gestures work as expected. Most users do not notice they are using a website rather than an installed app. This level of UI/UX design quality was previously only achievable with a dedicated native build, which typically costs twice as much to produce.

Cross-device responsiveness

One codebase adapts across screen sizes, from a 4-inch Android to a 27-inch desktop monitor. No separate mobile site. No feature gaps between what different devices support. This matters when users switch between a work laptop and their phone mid-session, which happens more often than most analytics dashboards reveal.

Instant installation

Rather than routing users through an app store, a PWA offers an “Add to Home Screen” prompt directly in the browser. One tap, and the icon appears on their device. The barrier between discovery and installation shrinks to nearly nothing.

Automatic updates

Version management is handled by the service worker update cycle, silently, without user action. The fragmentation problem that haunts native app ecosystems, where a meaningful proportion of users are always running outdated versions, simply does not apply here.

Push notifications

Browser-native push messages reach users even when the PWA is not open. This works across Android and, with growing support, on iOS. The re-engagement channel this creates is genuinely comparable to what native apps offer, without the app store dependency.

Search engine visibility

PWAs have standard URLs. Every page is fully crawlable from day one. Unlike native apps, which sit behind app store walls that search engine crawlers cannot penetrate, a PWA’s content is accessible to Google and Bing without any special configuration.

PWA vs native app: what actually changes?

Less than you might expect on the surface. More than you would think in the budget sheet.

Maintaining two native codebases (one for iOS and one for Android) means two development teams, two review cycles, two support queues, and two sets of platform fees. A PWA collapses that into one. For mobile application development projects where speed-to-market matters, that is a material 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?

Six outcomes come up consistently across businesses that have made the switch.

1. Lower development and maintenance costs

Building one PWA instead of two native apps typically reduces initial development spend by 30–50%. That is before accounting for what happens post-launch, where the savings compound: one codebase, one design system, one deployment pipeline. Teams managing custom software across platforms regularly cut maintenance budgets in half after switching from native. IT support and maintenance costs drop proportionally, since there is no iOS/Android divergence to manage separately.

2. Shorter time to market

A PWA built on React or Vue typically takes 8–16 weeks from specification to production. That is 30–40% faster than a comparable native build with separate iOS and Android review cycles. For teams working to an MVP development timeline, the difference often comes down to one quarter versus two.

3. Higher mobile conversion rates

Here is the persistent problem: mobile web traffic has overtaken desktop globally, but mobile conversion rates still lag well behind. PWAs close that gap. Friction disappears: no app store redirect, no download wait, no installation step before a user can engage. Alibaba’s 76% conversion increase across browsers after upgrading to a PWA is often cited, and the mechanism is straightforward. 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 in milliseconds 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 in the process. Push notifications extend this reach, connecting with users without requiring a return to 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. App store installs have several of them: leave the browser, find the store listing, download, grant permissions, then resume. PWAs eliminate all of that. 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

For e-commerce teams, PWAs work naturally with headless commerce architectures. Frontend and backend are decoupled, which gives marketing the freedom to iterate on product pages and checkout flows without waiting for backend releases. This is a core pattern in business process automation for retail and e-commerce operations. Frontend development and backend development teams work in parallel rather than in sequence, which sharpens release cadence considerably.

Are progressive web apps good for SEO?

Yes. The reasons are more technical than most people expect.

Start with a basic structural point: native app content is invisible to search engines. It sits behind app store walls that crawlers cannot penetrate. A PWA has standard URLs, and Google indexes it like any other website. That alone is a meaningful advantage if you are comparing a PWA strategy against a native-only strategy.

Beyond indexability, PWAs tend to score well on the signals Google uses to rank pages. Service workers deliver cached content in milliseconds on repeat visits, which directly supports Core Web Vitals performance, particularly Largest Contentful Paint and First Input Delay. Both are confirmed ranking factors.

Server-side rendering adds a further layer. When a PWA serves pre-rendered HTML rather than waiting for client-side JavaScript to build the page, crawlers receive complete content on the first request. Every page becomes fully indexable without special handling.

For software testing teams, Google Lighthouse audits PWA readiness across offline capability, HTTPS, manifest validity, and performance scores. It doubles as a solid SEO readiness check before launch.

Progressive web app examples: three companies that got it right

Pinterest

Pinterest’s 2017 rebuild is probably the most documented PWA case study that exists. The old mobile site took 23 seconds to load on 3G. The new PWA loaded in under 5. 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. Worth being precise about what that metric means: conversions on Alibaba correspond to direct contact between buyers and suppliers. That is a commercial outcome, not a vanity metric. 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, and on that hardware, the PWA outperformed the native app on almost every engagement metric.

The pattern across all three cases is the same. Remove friction from the mobile experience, and engagement follows. PWAs are a reliable mechanism for doing that.

What makes a good progressive web app?

Four components define the technical minimum. Google Lighthouse audits all four.

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 will not register on non-HTTPS origins. Full stop. It is not a best-practice recommendation — it is a hard technical constraint built into the specification. HTTPS is also a confirmed Google ranking factor and a baseline trust signal for users. For teams thinking through cloud data security, it is the floor, not the ceiling.

App icon

The icon that appears on the home screen after installation. Standard sizes: 512×512 pixels in PNG, with a 192×192 variant for Android. Small decision in isolation. First thing a returning user sees every time they open your app. It deserves the same attention as any other 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 a proportion of users. That is not a hypothesis. It is measurable in almost any analytics platform. A PWA addresses this by enabling one-tap sign-in, saved payment details, and autofill, without requiring a native app install first.

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

Mobile devices account for the majority of global web traffic. Native apps demand storage space, battery life, and a reliable connection just to download in the first place. A PWA delivers an equivalent experience at a fraction of the device cost.

That is especially relevant in markets where low-cost Android devices are the primary access point, which is exactly why Twitter prioritised PWA for its growth market strategy. For logistics and travel, and hospitality businesses with teams moving in and out of connectivity throughout the day, PWA has become the default approach rather than the experimental one. Building a web application strategy around mobile-first users without accounting for offline capability is increasingly difficult to justify.

Keeping users engaged after the session ends

Push notifications from a PWA appear on the lock screen, work with the browser closed, and can be personalised by behaviour. For hotel booking and travel platforms, ticket services, and subscription businesses, this is a meaningful re-engagement channel, and it requires no native app install from the user.

Key takeaways

Progressive web apps are not a compromise between websites and native apps. They are a deliberate architectural choice that removes the friction native apps create, without sacrificing the experience users expect from them.

Most businesses that make the switch report three things: lower development costs, stronger mobile engagement, and a faster path to market. The evidence from Pinterest, Alibaba, Twitter, and Starbucks is documented and reproducible.

The question is not whether the technology works. It does.

The question is whether your current mobile setup is costing you conversions it does not need to.

If you want to assess whether a PWA is the right next step for your product, the Go Wombat team can walk you through it. Talk to our engineers.