What is a Progressive Web App (PWA)?

Online stores like Amazon and Staples offer online services for product searching and selection, payment processing, and delivery tracking. Travel agencies like Booking and AirBnB offer map functionality, reservation processes, and messaging. Streaming services like Spotify offer search, play, and playlist management.

These big-name online services offer their services via web and mobile applications. Some of them build their apps using standard web-based programming languages. However, many small and large companies increasingly use Progressive Web Apps (PWA) to build their full-featured online applications.

Let’s explore PWAs, an approach to application development that uses a single code base to serve all devices and online channels. PWAs offer direct access to the most advanced web and mobile features and have numerous frameworks to help developers bootstrap and build the apps.

Additionally, PWAs offer device notifications, session storage, fast loading, and improved SEO over native apps. Business-wise, fewer engineers are needed initially to build a PWA and even fewer to maintain.

What exactly is a PWA?

Progressive web applications (PWAs) offer full application functionality, providing access to a company’s backend data and processes and direct access to a device’s features. Like any website, a PWA runs inside browsers like Google Chrome, Safari, and MS Edge, so users do not need to install or configure the application. They only need a correct URL and usually a login ID.

PWAs can be added to mobile device home screens, with favicons or app icons to appear just like an application, only they open up the browser versus a native application when clicked on.

To provide such functionality, developers create a manifest file and services.

The manifest is a JSON file that contains information, such as your PWA’s name and display-related information, that enables the PWA to run as a native app.

A PWA uses services to perform background operations on the company’s backend servers. Services run parallel to the user’s actions, processing requests transparently while the user interacts with the app. And they are often so fast that their response times go undetected by the user.

For example, users can move around seamlessly to access a company’s data and business logic—to view and select products on e-commerce or create playlists for streaming—while all that time, they are constantly interacting with the backend servers. Native-app websites do not readily offer these functions.

What is the difference between a native app and a PWA?

Not every internet application is a PWA. For example, Amazon does not use a PWA. So, what makes a PWA different from any standard web application that does not use PWA technology?

Amazon has created a native app (not a PWA), which means it has coded its application entirely from scratch. It uses a combination of server-side and client-side technologies to create a front-end app that, like a PWA, runs inside a browser.

So what is the difference? The amount of code is one—PWAs come with frameworks and libraries that give developers direct access to the browser and all of the Web APIs therein. Furthermore, a PWA has only one code base that works on all channels, mobile and desktop.

Additionally, PWAs are entirely JavaScript-driven. Web applications that do not use PWAs are server-side applications that push their functionality to the browser. They use the browser as a terminal. Server-side apps use server-side languages, such as Go, RUST, and .NET, to dynamically generate the JavaScript that will perform the client-side functionality. In contrast, the PWA is a JavaScript app that requests its JavaScript-coded services to perform actions.

PWA developers code in popular frameworks like React and create JavaScript services that perform all server-side actions. As a result, they run fast and integrate transparently into a browser, enabling many local-based app features, like sending user notifications to the mobile or providing offline access when the user is not connected to the web.

What is the difference between PWA and SPA?

A Single-Page App (SPA) and a Progressive Web App (PWA) serve different purposes and do not provide the same user experience. They share some of the same benefits, such as being entirely client-side and therefore fast and using the browser as part of their application, but they are functionally and technically different.

YouTube shorts and Instagram are SPAs that allow users to scroll down to see an endless feed of content. What makes SPAs so widely used is their ability to refresh complex content (videos, text, reactions, comments) seamlessly as the user scrolls. They are completely decoupled from the server, so they can use a headless architecture and advanced content systems to manage their content.

A PWA is a fully functional application that provides a native-like experience to users without the need for any application installation. They provide a menu, different pages, and multiple services, like ordering and account management, and more.

PWA examples: Twitter & Starbucks

Jeremy Keith, in the article "What is a progressive web app?” wrote:

“If you’re talking to the business people, tell them about the return on investment you get from progressive web apps. If you’re talking to the marketing people, tell them about the experiential benefits of progressive web apps. But if you’re talking to developers, tell them that a progressive web app is a website served over HTTPS with a service worker and manifest file.”

Twitter and Starbucks created browser-based PWAs as an alternative to their mobile apps. Thanks to a PWA's full functionality, device-based notification, offline abilities, speed, and immediate access without installation, the number of online users increased.

Pinterest increased its revenue thanks to PWA’s simplicity in integrating website-like Advertising. While Pinterest feed uses single-page application technology, its advertising and other more interactive features use PWA technology.

Companies can implement PWAs themselves or use an agency specialized in PWA. In both cases, because PWAs are already built with in-app notifications, offline access, speed, and many other such local-app features, and because they run on only one code base, the time to market on all channels is immeasurably faster than native apps.