What is a progressive web app (PWA), and how does it work?

Progressive web apps (PWAs) offer a number of advantages that make them an attractive choice for developers and users. One of the most prominent advantages is that PWAs can work offline or in poor network conditions. This is achieved using service workers, which cache content and allow access to the app’s features even when there is no internet connection.

In addition, PWAs are platform-independent and can run on any device with a modern web browser, which removes the need to develop separate apps for different operating systems such as iOS and Android. This reduces development costs and makes the app easier to maintain, as there is only one codebase to update.

Compared with traditional native apps, which require installation from an app store, PWAs can be accessed directly from a URL and added to the device’s home screen with a simple, lightweight installation directly from the browser. This provides a more streamlined user experience and lowers the barriers to starting to use the app, which can lead to higher user engagement and conversion rates.

A progressive web app (PWA) differs from a traditional native app by combining the best of web and mobile applications. A PWA is designed to run in a web browser, which means that it can be accessed from any device with internet access without the need for installation from an app store. This makes PWAs more accessible and easier to maintain, as they are updated automatically when the user reloads the app and the service worker fetches the new version.

In addition, PWAs can work offline or with a poor network connection using service workers, which cache important resources and data locally on the device; this is what distinguishes them from an ordinary responsive website. This provides an experience similar to a native app, even when there is no internet connection. PWAs can also send push notifications and access some of the device’s hardware features, such as the camera and GPS, which further blurs the boundaries between web and native apps, although native apps still have broader access to the device.

Compared with traditional native apps, which require separate versions for each platform (e.g. iOS and Android) and often higher development and maintenance costs, PWAs are more cost-effective and quicker to develop. They offer a consistent user experience across different devices and platforms, making them an attractive choice for many companies that want to reach a wider audience. A related idea was Instant Apps, in which parts of a native Android app could be opened without installation until Google shut down the feature in 2025.

Building an effective progressive web app (PWA) requires a combination of several technologies and tools that together provide an app-like experience directly in the web browser. Here are the key components that make a PWA both functional and user-friendly:

• Service workers: Service workers are one of the most crucial technologies behind PWAs. They act as a proxy between the web application and the network, enabling offline functionality and, in browsers that support it, background synchronisation. Service workers can cache resources so that users can access the app without an internet connection, which significantly improves the user experience.
• Web app manifest: This JSON file format enables developers to define the app’s metadata, such as name, icons, theme and start URL. The manifest makes it possible for users to install the PWA on their devices so that it behaves like a native app with a home screen icon and full-screen display.
• Responsive design: To ensure an optimal user experience across different devices and screen sizes, responsive design is crucial. Using CSS and flexible layouts, PWAs can adapt to everything from small mobile screens to large desktops, ensuring a consistent experience.
• HTTPS: Security is a fundamental component of PWAs, and HTTPS is a requirement for implementing service workers. HTTPS ensures that data transfers between the user and the server are encrypted, which protects against man-in-the-middle attacks and other security threats.
• Push notifications: Push notifications enable PWAs to engage users even when the app is not active. By sending relevant and timely messages, developers can keep users up to date and increase interaction with the app.

The combination of these technologies and tools makes it possible to create PWAs that deliver a fast, reliable and engaging experience that can compete with native apps.

A progressive web app (PWA) can improve the user experience compared with an ordinary web application through several key features:

• Offline access: PWAs can work without an internet connection by caching data locally. This means that users can continue using the app even when they are offline, which is a major advantage in areas with poor or no network coverage.
• Faster loading times: Thanks to caching and optimised resources, PWAs can load much faster than traditional web applications on repeat visits. This significantly improves the user experience, as waiting time is reduced.
• Push notifications: PWAs can send push notifications to users even when the app is not open. This enables developers to engage users with updates, offers or reminders, which increases user interaction.
• Responsive design: PWAs are designed to work across different devices and screen sizes, ensuring a consistent and optimal experience whether the user is on a smartphone, tablet or desktop.
• Installation without an app store: Users can install PWAs directly from the browser without going through an app store. This makes the installation process faster and more convenient while removing barriers to access.
• Security: PWAs run over HTTPS, which ensures that data transfers are encrypted and protected against interception and manipulation. This gives users a high degree of security and trust.
• Automatic updates: PWAs are updated automatically in the background, ensuring that users always have access to the latest version without having to download updates manually.

Overall, PWAs combine offline functionality, faster loading times, push notifications, responsive design, easy installation, security and automatic updates to deliver a superior user experience. This makes PWAs an attractive choice for both developers and users who want an app-like experience without the traditional constraints of native apps.

Progressive web apps (PWAs) offer a number of advantages, including offline access, push notifications and an app-like experience directly in the browser. However, these advantages also come with a number of security considerations that developers must take into account to protect users’ data and ensure a secure user experience.

HTTPS as the basis for security: One of the most fundamental security requirements for PWAs is the use of HTTPS. HTTPS ensures that data sent between the user and the server is encrypted, which protects against man-in-the-middle attacks. Browsers require HTTPS to enable many of the advanced PWA features, such as service workers and push notifications.

Service workers and their security: Service workers are a central component of PWAs that enable offline functionality and background synchronisation. It is important to ensure that service workers have a scope limited to the parts of the site they need and that they are correctly configured to handle errors and avoid caching sensitive responses. Regular updating and maintenance of service workers is crucial for preventing security vulnerabilities.

Data handling and local storage: PWAs can store data locally on the user’s device to improve performance and availability. It is important to ensure that sensitive data is protected and that there are clear policies for how data is handled and deleted. The use of IndexedDB or LocalStorage should be carefully considered, as data there can be read by any script on the same origin, and mechanisms to protect against XSS attacks, such as a Content Security Policy, should be implemented.

Authentication and authorisation: To protect users’ accounts and data, PWAs should implement strong authentication methods, for example based on OAuth 2.0 and OpenID Connect, or passkeys. Two-factor authentication (2FA) can also be added as an extra layer of security. It is important to ensure that sessions are handled correctly and that mechanisms exist to prevent unauthorised access.

Regular security testing and updates: To ensure that the PWA remains secure over time, regular security tests and updates should be carried out. This includes penetration tests, code reviews and updating dependencies to protect against known vulnerabilities. A proactive approach to security can help identify and mitigate potential threats before they are exploited.

By taking these security considerations into account, developers can create PWAs that not only deliver an excellent user experience but also protect users’ data and privacy.

Progressive web apps (PWAs) are an innovative technology that can play a crucial role in increasing engagement and conversion for companies. By combining the best of web and mobile apps, PWAs offer a seamless and engaging user experience that can attract and retain customers.

A PWA works by using modern web technologies to deliver an app-like experience directly in the user’s browser. This means that users can access the app without downloading it from an app store, which reduces friction and makes it easier for them to interact with the company. PWAs can be installed on the user’s home screen, which provides easy access and increases the likelihood of repeat visits.

One of the most significant advantages of PWAs is their ability to work offline or in poor network conditions. This is achieved through the use of service workers, which cache content and ensure that users can continue to interact with the app even without an internet connection. This functionality can be crucial for maintaining users’ interest and preventing them from leaving the app when the connection is unstable.

In addition, PWAs support push notifications, which can be used to engage users with relevant updates and offers. Push notifications can be personalised and targeted, which increases the chances of users responding positively and converting. By delivering valuable content and incentives directly to the user’s device, companies can build stronger relationships and increase customer loyalty.

This combination of accessibility, offline functionality and targeted communication makes PWAs a powerful tool for companies that want to improve user engagement and conversion rates.