What is a .apk file?
Android Package · Disk image · Google · 2008
An APK is an Android app installer. It is a signed ZIP bundle containing the app's code and resources, and it is what you install when you add an app outside the Play Store, so trust the source before you do.
What is a .apk file used for?
An APK packages everything an Android app needs: compiled code, images, and a manifest, all signed to prove who built it.
The Play Store installs APKs for you behind the scenes. Installing one manually, called sideloading, is useful but skips the store's safety checks.
Because it installs a running app, an APK from an unknown source carries the same risk as any executable.
What opens a .apk file?
The .apk format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Android emulator
- 7-Zip (to inspect)
macOS
- Android emulator
- 7-Zip (to inspect)
Linux
- Android emulator
- unzip (to inspect)
Web
- Not applicable
Open a .apk file step by step
- Confirm the file really is a .apk. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Android emulator or 7-Zip (to inspect).
- On Mac, use Android emulator or 7-Zip (to inspect).
- On Linux, try Android emulator or unzip (to inspect).
- Still stuck? Convert the .apk to Not convertible, which opens more widely.
Why can't I open my .apk file?
Almost always because no installed app understands APK. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .apk at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .apk file
You can convert a .apk file to Not convertible using a conversion tool or the export menu of an app that opens it.
What is the .apk file signature (magic bytes)?
A .apk file starts with the hex bytes 50 4B 03 04, which read as PK.. in ASCII. Programs identify APK by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for APK. For a full breakdown, see the ZIP file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 50 4B 03 04 | 0 | PK.. | ZIP header (APK is a signed ZIP) |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .apk file?
An APK is an Android app installer. It is a signed ZIP bundle containing the app's code and resources, and it is what you install when you add an app outside the Play Store, so trust the source before you do.
How do I install an APK?
On Android, enable installing from unknown sources for your browser or file manager, then open the APK. Only do this for apps from trusted developers.
Related formats
Sources
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