Cross-Platform Apps

Web and mobile apps are now the most preferred versions of applications for both personal and business use. Applications are accessed from personal computers, tablets, and smartphones. While this has resulted in an excellent user experience, it has added new challenges to application developers.

There are two major design and development differences in applications on each device:

• First, the screen sizes of smartphones are significantly smaller than those of personal computers or tablets. Tablets and smartphones use touchscreens as input devices while computers use keyboards and mice.

• Second, The devices have different operating systems. Computers use Windows, macOS or Linux while tablets and smartphones use Android and iOS. Each operating system provides the services that apps can use to interact with the hardware. Each operating system specifies how apps for that operating system should be developed.

This is a problem for developers because every app now needs to have multiple versions only to support these screen size and operating system variations (while the functionality has to remain exactly the same). This results in increased efforts and cost of development, support, and maintenance.

Native Apps

Mobile apps developed for a specific operating system are known as native apps. Native apps built for iOS cannot be used on Android phones and vice versa. The main advantage of native apps is that they provide a good user experience and high performance. Also, both Google (for Android) and Apple (for iOS) have created an ecosystem known as app stores, from where apps for their operating system can be downloaded. With app stores managed by trusted entities, apps are validated for security and integrity that keeps users' phones safe. Phones generally do not allow the installation of apps from any source other than the respective app stores.

There are two approaches that can be followed to overcome the overhead of developing native apps and a separate web version of the app:

• Build Cross-Platform Apps
• Build Responsive Apps

Cross-Platform Apps

Technology stacks have been developed that allow developers to write applications in HTML5, CSS, and JavaScript, and one version of the source code can be compiled into web applications or Android and iOS native apps. This approach is referred to as building cross-platform apps.

Responsive Apps

CSS provides a programming option that allows developers to change the layout of the web page depending on the size of the screen. Using this option, web pages can be programmed to make them accessible, either on a computer or a smartphone. The layout and element attributes (such as font or image sizes) will adjust themselves to match the screen size, but the functionality will be the same since it is all handled by the server-side code.

The major advantage of this approach is that developers need to work on a single version of the code that is accessible across both web and mobile views and across all operating systems, thus significantly reducing development, support, and maintenance efforts and costs. Also, users do not need to download, install, or upgrade apps on their smartphones, as they can use a browser on their smartphones to access responsive apps.

The disadvantage of this approach is that responsive apps may not be able to use some smartphone features and can therefore only be used in apps where smartphone features aren't necessary.

Progressive Web Apps

A new architectural approach slowly becoming popular is known as Progressive Web Apps (PWAs). These fall in between responsive apps and native apps in terms of their ease of development and functionality. While responsive web apps are slower and offer fewer features, PWAs running on smartphones can perform much faster and provide almost as many features as native apps, in addition to being portable across both desktop and mobile platforms.

Every business and development team must decide what is the best approach for their requirement.

For this, there are three programming languages that are used universally for developing web and mobile apps, HTML, CSS, and JavaScript.