zipalignis a zip archive alignment tool that helps ensure that all uncompressed files
in the archive
are aligned relative to the start of the file. This lets the files be accessed directly via
mmap(2)
,removing the need to copy this data in RAM and reducing your app's memory usage.
Usezipalignto optimize your APK file before distributing it to
end users. If you build using Android Studio, which uses the Android Gradle plugin (AGP), this is
done automatically. In this case, you should still usezipalignto verify that the APK
is aligned, but you don't need to align it. This documentation is mainly for maintainers of
custom build systems.
Caution:You must usezipalignat a specific point in
the build process. That point depends on which app-signing tool you use:
To achieve alignment,zipalignalters the size of the"extra"field in the zipLocal File Header
sections. This process can also alter existing data in the"extra"fields.
Usage
If your APK contains shared libraries (.sofiles), use-p
to ensure that they're aligned to a 4KiB page boundary suitable formmap(2).For
other files, whose alignment is determined by the mandatory alignment argument to
zipalign,Android Studio aligns to 4 bytes on both 32-bit and 64-bit systems.
To aligninfile.apkand save it asoutfile.apk:
zipalign -p -f -v 4 infile.apk outfile.apk
To confirm the alignment ofexisting.apk,use the following command. If you use
Android Studio or AGP to build, this is the command you should use to verify that your APK is
aligned.
zipalign -c -v 4 existing.apk
Options
The following table lists the availablezipalignoptions:
| Option | Description |
|---|---|
| -c | Checks alignment only (does not modify file). |
| -f | Overwrites existing output file. |
| -h | Displays tool help. |
| -p | Page-aligns uncompressed.sofiles. |
| -v | Verbose output. |
| -z | Recompresses using Zopfli. |