Here's a list of a few free and safe websites to install third-party Android APKs that are not available on the Google Play Store.
Prior to posting the APKs on the platform, the APKPure website thoroughly examines their credibility.
F-Droid is a platform for users who enjoy installing and playing with open-source apps on their Android smartphones.
APKMirror offers a significant collection of APKs in a variety of genres with newest and most popular games and useful apps.
Users of APK Downloader, that has a large selection of apps, are able to search for their preferred apps using a Play Store URL.
Softpedia is one such platform that lets users to download APKs for Android, Mac, Windows, and Linux systems.
One of the earliest, Aptoide, functions as a reliable alternative for Google Play Store with a similar UI and full app descriptions.
It provides even open-source games along with all types of software for Android, Windows, and Mac users to download.
APK4Fun provides older versions of all apps in addition to the most recent ones, and it authenticates them with a SHA1 certificate.