What is sideloading?
Sideloading is the installation of an application on a mobile device without using the device's official application distribution method. These days, most users acquire their applications through a sanctioned app store, such as Google Play, Microsoft Store, Samsung Galaxy Store or Apple's App Store. Despite the millions of apps that these stores contain, users might still want to acquire apps from other sources, in which case they must sideload the apps onto their devices, an operation that comes with both advantages and risks.
The term sideloading has traditionally referred to the process of transferring files between two devices. The devices are usually connected by a cable or wireless network, although someone might instead use a memory card or external storage drive to move the files from one device to another. For example, a user might transfer documents between two PCs connected by a cable. Sideloading, in this sense, can be contrasted to downloading or uploading files, which are concerned with transferring files between local devices and remote servers.
Since the introduction of smartphones, sideloading has come to refer primarily to the process of installing apps on devices through unapproved channels. Although the term sideloading is generally used for mobile devices, it can refer to other devices as well, such as laptops or desktops.
App sideloading offers users a way to access more applications than are available through the sanctioned channels. However, users should understand that sideloading unapproved apps can pose significant risks. The sanctioned app stores screen for malware and other threats and assume responsibility for digital rights management. Third-party apps might not be screened for malware, might be pirated or a combination of both.
How does sideloading work?
Sideloading works differently from one platform to the next. On Windows and macOS computers, users can install apps from just about anywhere. There might be additional steps the user must take depending on the platform, but those are usually easy to carry out. For example, Windows 11 includes a setting for specifying whether apps need to come exclusively from the Microsoft Store or if they can come from other sources. That setting might need to be adjusted to permit sideloading on a particular Windows computer.
The process is a little different on macOS computers. On these systems, users can specify whether apps must come exclusively from the App Store or if they can also come from identified developers. Users can still sideload apps from nonidentified developers, but this process involves a couple additional steps, although they're relatively minor. Mac users also have the option to use a package manager, such as Homebrew, to install apps on their systems.
App sideloading on Android devices is also relatively straightforward. The user first downloads the application file to the device. The user then taps on the file to install it, at which point the user is prompted to trust the app source. Once the source has been trusted, the app installation process continues.
Apple makes sideloading much more difficult on its iOS devices, although the process has gotten slightly easier in recent years. At one time, users would need to jailbreak their devices to enable sideloading. Only then could they download and install applications from third-party websites or app stores.
Apple has loosened up a bit since then, and it is now possible to sideload apps through other means. For example, developers can use the Xcode integrated development environment on their Mac computers to connect to iOS devices and sideload the apps that they're building. Another option is to use software such as AltStore or Sideloadly to sideload apps on iOS devices. This approach requires the user to install the app on their Mac or Windows computer, connect the computer to the iOS device and carry out several additional steps to prepare the iOS device for sideloading apps.
Apple might soon be forced to make it much easier to sideload apps on iOS devices, at least in some parts of the world. The European Union (EU) recently passed the Digital Markets Act, which regulates the power of large digital companies, such as Apple. One of the consequences of this act is that Apple will soon have to allow sideloading on all iOS devices sold in the EU. Japan is also on course to pass a similar law. It is unknown whether Apple will eventually permit sideloading in other countries or regions or wait until it's forced to do so. The company has always strongly opposed allowing sideloading on iOS devices.
See how to sideload iOS apps and why it's dangerous, and learn how to protect mobile devices from malware in the enterprise. Ensuring the security of work-related data and communication on smartphones is a huge challenge. Learn more about mobile device security with this guide.