Progressive Web Apps: Native-Like Experiences Without App Store Distribution

Progressive Web Apps (PWAs) bridge the gap between web and native mobile experiences, offering installability, offline access, and push notifications through standard web technologies. For businesses in Bangladesh, where affordable Android devices dominate and data connectivity remains inconsistent outside urban centers, PWAs offer a compelling distribution strategy that bypasses app store gatekeeping entirely.

Service Workers: The Foundation

Service workers are JavaScript files that run in a separate thread from the main browser context, acting as a programmable proxy between the web application and the network. They intercept fetch requests, manage caching strategies, and enable background synchronization. Registration is straightforward but requires HTTPS in production.

The most common caching strategies include Cache First (serve from cache, fall back to network), Network First (attempt network, fall back to cache), and Stale While Revalidate (serve cached content immediately while fetching an updated version in the background). Choosing the right strategy depends on your content type—static assets benefit from Cache First, while API responses often work best with Stale While Revalidate.

Offline Capability and the App Shell

The App Shell architecture separates the minimal HTML, CSS, and JavaScript needed to render the application skeleton from the dynamic content. The shell is cached during the initial service worker installation, ensuring the app loads instantly on subsequent visits—even without connectivity. Dynamic content is then fetched and injected as it becomes available.

For data-driven applications, IndexedDB provides a robust client-side database for storing structured data offline. Libraries like Dexie.js wrap IndexedDB in a more ergonomic API, making it practical to implement offline queues for form submissions, transaction records, and other user-generated data that syncs when connectivity returns.

Web Push Notifications

PWAs can send push notifications using the Push API and the Notifications API. The flow involves requesting user permission, subscribing to a push service (typically via the browser's built-in push service endpoint), and storing the subscription on your server. When you need to send a notification, your server sends a payload to the push service, which delivers it to the user's device.

Web push uses the VAPID (Voluntary Application Server Identification) protocol for authentication. Server-side libraries for Node.js, Python, and PHP handle the encryption and delivery mechanics. Notification payloads should be concise—title, body, icon, and an action URL—to maximize engagement without overwhelming users.

Installability and the Web App Manifest

The web app manifest is a JSON file that defines how the PWA appears when installed on a device: its name, icons, theme color, display mode, and start URL. Setting the display property to standalone removes the browser chrome, making the app visually indistinguishable from a native application. Chrome on Android prompts users to install PWAs that meet specific criteria: served over HTTPS, registered service worker, and a valid manifest.

Installation rates improve dramatically when prompted contextually—for example, after a user completes a key action rather than on the first page load. Custom install prompts using the beforeinstallprompt event give developers full control over the timing and presentation of the installation flow.

Performance Considerations

PWAs must load fast to compete with native apps. Target a Largest Contentful Paint (LCP) under 2.5 seconds and a First Input Delay (FID) under 100 milliseconds. Precaching critical assets during service worker installation, using code splitting to reduce initial bundle size, and lazy-loading images with the loading="lazy" attribute are essential optimizations.

In the Bangladeshi market, where users frequently operate on 3G or intermittent connections, aggressive caching and optimized asset delivery are not optional—they are the difference between a usable application and an abandoned one.

PWAs at Nexis Limited

We have built PWAs for clients who needed broad reach without the overhead of app store management. Our Digital Menu product leverages PWA principles for instant access in restaurant environments. Explore our full range of mobile development services or contact us to discuss whether a PWA fits your project requirements.