Before you start
Installing the KhoindVN APK takes about a minute and one small permission change. You will need an Android phone running version 5.0 or newer, a few seconds of internet to fetch the 13 KB file, and the willingness to tap through one system warning that sounds worse than it is.
Start at the download KhoindVN APK page on this site. That page serves the exact file our test phones verified, so there is no reason to hunt for the APK anywhere else.
Step 1: fetch the file
On the download page, wait out the short six-second timer, then tap the download button that appears. Your browser will fetch khoindvn.apk, about 13 KB. On most connections this finishes before you can blink; on a slow one, give it a few seconds and check that the file size reads roughly 13 KB when done.
If your browser warns that the file "might be harmful," that is the standard caution for any APK downloaded in a browser. It appears for every sideloaded app and is not a verdict on this file.
Step 2: open the package
Pull down the notification shade and tap the finished download, or open your Downloads folder and tap khoindvn.apk. Android will open its package installer and show you the app name, KhoindVN, and the single permission it requests: internet access.
Take a second to look at that permission list. One permission, plainly explained on our safety page, is exactly what a WebView wrapper should ask for.
Step 3: allow the install
Android will ask you to allow your browser to install unknown apps. This is the one permission change the process needs. Tap Settings on the prompt, toggle Allow from this source, and go back. Then tap Install on the system dialog.
You can switch the toggle back off afterward; the app stays installed either way. The permission only controls whether that browser may start installs, nothing else.
Step 4: open and place the icon
Tap Open when the installer finishes. The khoindvn.io.vn site loads inside the app window. Long-press the new KhoindVN icon in your app drawer to drag it onto your home screen, somewhere you will actually tap it.
If anything misbehaves along the way, our install-error fixes cover the common failures, and the general safe sideloading guide explains the principles behind each step.