APK vs AAB vs XAPK: What Each Android File Type Means
Image: Jernej Furman from Slovenia, CC BY 2.0, via Wikimedia Commons
If you have browsed download pages for Android apps you have probably met more file types than you expected: APK, AAB, XAPK, APKM, APKS and OBB. They look similar, yet only some can be installed with a tap. This guide explains each one and what to do when you meet it.
APK: the installable package
APK stands for Android Package. It is a single archive containing the app’s code, resources and a signature from its developer. Tap it and Android can install it. Older apps and many simple apps are distributed as a single APK.
AAB: the format developers upload to Google Play
An Android App Bundle (AAB) is the publishing format Google Play expects from developers. It contains everything the app needs for every device, but you cannot install an AAB on a phone. When someone installs the app from Play, Google builds a set of optimised APKs from the bundle for that device: the right processor code, the right screen density and the right language. The benefit is smaller downloads. Developers use Google’s bundletool to turn bundles into installable APK sets for testing.
Split APKs: what Play actually installs
An app delivered from a bundle is installed as a base APK plus several split APKs, for example base.apk, split_config.arm64_v8a.apk and split_config.xxhdpi.apk. All of them must be installed together. If you try to install only the base file, the app may refuse to start or fail to install.
XAPK, APKM and APKS: bundles made by third parties
These are not official Android formats. Each is a container, usually a zip file, that holds a base APK, one or more split APKs and sometimes extra game data.
| Format | Made by | Contains | Needs |
|---|---|---|---|
| XAPK | Download sites and community tools | APKs, OBB data, a manifest | An installer app, or manual steps |
| APKM | APKMirror | Split APKs | APKMirror Installer |
| APKS | bundletool and installer apps | Split APKs | An installer app, or adb |
Your phone cannot open these by tapping, so a download page that supplies one will usually tell you to install a helper app. That is one more program to trust. Prefer a plain APK when one exists, and check the helper tool as carefully as the app itself (see our safety checklist).
OBB: expansion data for big games
Some older games keep large assets in an OBB expansion file, stored in Android/obb/ followed by the package name. Modern games mostly use Play Asset Delivery or download extra data on first launch instead. Android 11 and later restrict how apps and file managers can access those folders, so manual copying is harder than it used to be.
How to install each type
A plain APK
Tap it and follow the step-by-step install guide.
A set of split APKs
Use an installer app that supports splits, or connect your phone to a computer and run adb install-multiple base.apk split_config.arm64_v8a.apk, listing every file in the set.
An XAPK
Open it with a trusted installer, or unzip it, install the APK files inside as a set and copy any OBB folder to Android/obb/ before the first launch.
An AAB
You cannot install it directly. Look for the same app on Google Play instead, or ask the developer for an APK build.
Which file should you choose?
- If Google Play offers the app in your region, use Play. It handles splits, signatures and updates for you.
- If you need an APK, choose a universal single APK for your Android version.
- Use bundles only when nothing else exists, and only from sources you trust.
Before downloading any of them, confirm that your phone meets the minimum version, as explained in our guide to Requires Android.
Common mistakes with bundles
- Installing only the base APK. A bundle usually needs the base file and its split files installed together.
- Mixing splits from different versions. Every file in a set must come from the same version of the app, or the install fails or the app crashes.
- Skipping the OBB folder. A game installed without its data will often show an error or a download screen on first launch.
- Trusting the helper app blindly. An installer app has broad access to install other software, so get it from a reputable source and check it as carefully as the app you want.
Frequently asked questions
Can I convert an AAB to an APK?
Developers can, using bundletool, which builds installable APK sets from a bundle for a chosen device. For most people it is simpler to install the app from Google Play or ask the developer for an APK.
Is an XAPK safer than an APK?
No. An XAPK is only a container. It is as safe as the files inside it and the source it came from, and it adds the extra risk of needing an installer app.
Why are some apps split into several files?
Splitting lets Google Play send only the code, graphics and languages your device needs, which makes downloads smaller.