Q.Why are some programs not available in the software app stores, even if I know they exist? If I find them anyway, are they safe to install?
A. The “app store” approach to distributing software, which downloads the program directly to the device (or computer), is a convenience for consumers, but not every developer chooses to sell work that way. For one, the bigger electronic marketplaces run by Apple, Google and Microsoftplace technical restrictions on what a program can and cannot do once it is installed, and some software creators do not wish to abide by those rules.
Other developers may also balk at registration fees and the revenue-sharing policy of an online app emporium. Apple, Google and Microsoft often take a 30-percent cut of the sales in their app stores, although some in-app subscriptions now require only 15 percent of the overall price as payment.
Certain programs you seek may not be available for other reasons, like regional restrictions or the creator pulling a program from the store. If you are looking for an app you know exists, make sure any parental-control settings on your device are not blocking you from seeing the software.
Apps approved for sale in Apple’s App Store (and Mac App Store), the Google Playstore and Microsoft’s Windows Store have presumably been screened for quality and security, which is one advantage to buying programs there. While it often takes some extra work, manually installing third-party apps from unofficial sources is possible; the practice is also known as sideloading.
In some cases — particularly with Apple’s devices — you may need to “jailbreak” or “root” your gadget to override the manufacturer’s protections and install unauthorized software. Proceed at your own risk, however, as manufacturers warn this may lead to security issues and possibly a voided warranty.
Long before smartphones and tablets arrived, developers were selling their wares as downloads from their websites or offering them in software repositories (like those used by many Linux distributions). You can still install many desktop programs this way. Just make sure that the seller is legitimate and that the security software on your computer is activated and up-to-date.