Progressive Web Apps (PWAs) have been generating buzz for several years, but 2019 is the year they are truly hitting their stride. With substantially improved browser support, proven success stories from major brands, and a growing ecosystem of tools and best practices, PWAs offer a compelling option for businesses seeking app-like experiences without the cost and complexity of native app development.
What Makes a Progressive Web App?
A Progressive Web App is a web application that uses modern web capabilities to deliver an experience that is indistinguishable from a native app in many respects. The term "progressive" refers to the fact that these apps work for every user regardless of their browser or device, progressively enhancing the experience when advanced features are available.
The Three Core Qualities
- Reliable — PWAs load instantly, even on unreliable or slow networks. Service workers cache essential resources, meaning the app can launch and function even when the device is completely offline.
- Fast — Interactions feel immediate. Smooth animations, rapid navigation, and responsive touch handling create an experience that rivals native applications.
- Engaging — PWAs can be installed on the home screen, receive push notifications, and run in a full-screen mode without a browser address bar. They feel like a natural part of the device.
The Core Technologies
Service Workers
Service workers are the foundation of any PWA. They are JavaScript files that run in the background, separate from the main browser thread, acting as a programmable proxy between the web application and the network.
**What service workers enable:** - **Offline functionality** — Cache critical resources so the app works without a network connection - **Background sync** — Queue actions taken offline and execute them when connectivity returns - **Push notifications** — Receive and display notifications even when the app is not open - **Smart caching strategies** — Cache-first for static assets, network-first for dynamic data, stale-while-revalidate for the best of both worlds
The Web App Manifest
The web app manifest is a JSON file that tells the browser how the application should behave when installed on a device. It defines the app's name, icons, theme colours, display mode (full screen, standalone, or browser), and the URL that opens when the app is launched.
A well-configured manifest enables the browser to prompt users to "Add to Home Screen," creating a shortcut that launches the app in a standalone window — indistinguishable from a native app to the average user.
HTTPS
PWAs require secure connections. This is not merely a technical requirement — HTTPS builds user trust, protects data in transit, and is essential for service worker functionality. Search engines also favour HTTPS sites, so this requirement aligns with broader best practices.
Real-World Success Stories
The business results from PWA adoption are compelling:
- Twitter Lite — Achieved a 65% increase in pages per session, 75% increase in tweets sent, and 20% decrease in bounce rate. The PWA is significantly faster than their previous mobile web experience.
- Pinterest — Reported a 60% increase in core engagements, a 44% increase in user-generated ad revenue, and a 40% increase in time spent on the site.
- Starbucks — Their PWA is 99.84% smaller than their native iOS app and has doubled the number of daily active users who order via the web. It functions fully offline, allowing customers to browse the menu and customise orders without connectivity.
- Trivago — Saw a 150% increase in engagement after launching their PWA, with users adding it to their home screens at a significantly higher rate than visiting the mobile site.
These are not niche businesses experimenting with new technology — they are major brands achieving measurable results.
When a PWA Is the Right Choice
PWAs are an excellent fit in several scenarios:
- Cross-platform reach with a single codebase — One PWA works across Android, iOS, Windows, and any device with a modern browser
- Budget constraints — Building and maintaining native apps for multiple platforms is expensive; a PWA significantly reduces that cost
- Content-heavy applications — News sites, e-commerce catalogues, and information portals benefit greatly from PWA patterns
- Users on slower networks or older devices — PWAs are designed to be lightweight and to function in constrained environments
- Rapid deployment — PWA updates are deployed instantly via the web, without app store review cycles
When to Consider Native Instead
PWAs are not the right choice for every situation:
- Hardware-intensive applications — Games, augmented reality, and applications requiring advanced camera or Bluetooth access may need native capabilities
- Platform-specific features — Some iOS and Android features are only available through native APIs
- App store presence is essential — If your distribution strategy depends on app store visibility and discoverability, a native app is necessary (though it is worth noting that PWAs can now be submitted to the Google Play Store)
Limitations to Be Aware Of
Honesty about limitations is important for making good technology decisions:
- iOS support is improving but lagging — Safari's service worker support is more restricted than Chrome's. Push notifications, background sync, and some caching strategies are limited on iOS.
- Native API access — Certain device capabilities (NFC, Bluetooth, advanced camera controls, contacts) are not yet available to PWAs, though the list of supported APIs grows with each browser release
- User awareness — Many users are not yet familiar with installing web apps; clear prompts and guidance help
- Storage limitations — Browsers impose storage limits on cached data, which can be a constraint for data-heavy applications
Building a PWA: Key Considerations
If you are considering a PWA for your business, keep these principles in mind:
- Start with performance — A slow PWA is just a slow website. Optimise aggressively.
- Design for offline gracefully — Decide what functionality should be available offline and implement appropriate caching strategies
- Test across browsers and devices — Particularly test on iOS where behaviour differs from Android
- Consider the installation prompt — Time the "Add to Home Screen" prompt thoughtfully; showing it too early is intrusive
- Implement analytics — Track PWA-specific metrics like installation rates, offline usage, and push notification engagement
At GRDJ Technology, we have been building progressive web apps for clients who want the reach and accessibility of the web combined with the engagement and performance of native apps. If a PWA aligns with your business goals, we can help you build one that performs well across every device and network condition.