A progressive web app (PWA) is a website built with standard web technologies that can also behave like an installed app: it can sit on the home screen, open in its own window, keep key screens available offline and, on supported devices, send notifications. For Hong Kong SMEs choosing between a website, a PWA and a native app, it sits in the middle: one web codebase with app-like features.
What makes a website a PWA
- Web app manifest: a small JSON file that sets the app's name, icons, start page and display mode, such as opening without the browser address bar.
- Service worker: a script the browser runs separately from the page. It can intercept network requests, cache files and respond when the network is slow or missing. It also handles push messages.
- Offline caching: chosen pages and data are kept on the device, so main screens load offline or show a clear offline message.
- HTTPS: service workers only run on secure connections, so a valid SSL certificate is required.
- Push notifications (optional): with the user's permission, your server can send notifications where the platform supports them.
Installing a PWA usually just adds an icon to the home screen or desktop; no app store download is involved.
Website, PWA or native app
- Regular website: opens in a browser tab, needs a connection for most pages and is found through search and links.
- PWA: the same web code and URLs, plus installation, offline screens and, where supported, notifications. Updates go live when you deploy, without app store review.
- Native app: built for iOS and Android and distributed through the App Store and Google Play. It gets the deepest access to device features and background processing but needs store review for each release.
Benefits for a small business
- One codebase across devices. Phones, tablets and desktops run the same app, often with a smaller scope than two native apps.
- No store step. Customers open a link, then install if they use it often.
- Faster updates. A fix on the server reaches users once the service worker picks up the new version.
- Quicker repeat visits. Caching, combined with a CDN for static files, can make return visits feel faster.
Real limitations to plan for
- Platform differences. Support for installation, notifications and background features varies by browser and operating system, and changes over time. Apple's documentation describes web push on iPhone and iPad (iOS and iPadOS 16.4 or later) for web apps added to the Home Screen, not for pages in an ordinary Safari tab. Check current documentation before promising features.
- Limited device access. Some hardware and system features open to native apps may be restricted in the browser. If you need Bluetooth or background location, test on target devices early.
- Offline needs design. Someone must decide what is cached, for how long, and what happens to a form submitted offline. Browsers may clear stored data, so the server should stay the main record.
- Different discovery. A PWA is not in app stores by default; listing one needs extra packaging.
- Stale versions. A poor cache strategy can leave users on an old version, so test updates in a staging environment first.
When a PWA makes sense
A PWA often fits when people return regularly for bookings, catalogues, forms or dashboards, and you want one product for mobile and desktop. It also suits testing an idea as an MVP. A native app may be better when the core value depends on device hardware, heavy offline use or an app store presence customers expect. A regular website is often enough when visitors mainly read information.
Illustrative example: A tutoring centre wants parents to check class schedules and get reminders. A PWA could let parents install the schedule, view it offline and opt in to web push reminders where supported, with email as the fallback.
Checklist before commissioning a PWA
- Which devices and browsers do your users use, and which features must work on each?
- Which screens must work offline, and what do users see when data cannot sync?
- Do you need push notifications, and what is the fallback?
- Which systems will it connect to through an API, such as booking or payments?
- How will updates be tested, and who checks that cached versions refresh?
- Who maintains the app, hosting and certificate after launch?
To compare options, see our mobile, web and WeChat app development page, or our website and web app development service.
Frequently asked questions
Is a PWA the same as a responsive website?
No. A responsive website adapts its layout to the screen. A PWA is usually responsive too, and adds a manifest and service worker for installation and offline use.
Does a PWA work on iPhone?
It opens in the browser like any website, and users can add it to the Home Screen. Features such as web push depend on the iOS version and on the app being added to the Home Screen. Test on your customers' devices.
Can an existing website become a PWA?
Often, by adding a manifest, a service worker and HTTPS. The effort depends on how the site is built and how much offline behaviour you need.
Will a PWA replace our native app?
Sometimes. If the app mainly shows content and forms, a PWA may cover most needs. If it relies on device hardware or store presence, compare both before deciding.