zipalign

Align the data of a Zip file on 4-byte boundaries

$ zipalign [4] [path/to/input.zip] [path/to/output.zip]

$ zipalign -v -c [4] [path/to/input.zip]

zipalign [-f -v]

-f
    Force overwriting of the existing outfile.zip.

-v
    Verbose output. Displays additional information during the alignment process.


    Byte alignment, e.g. 4 for 4-byte alignment (recommended for Android applications).


    The input zip archive file (e.g., an Android APK).


    The output zip archive file with aligned data.

The zipalign tool is an archive alignment utility that optimizes .apk files for Android operating system. Its primary function is to align all uncompressed data within the zip archive, such as resources and native libraries, to specific byte boundaries (typically 4-byte boundaries, but often 4KiB for optimized access).

By aligning the data, zipalign improves application performance by reducing the amount of memory required when loading an application, because the Android runtime can directly map aligned data in memory without having to copy it from archive to memory.

Proper alignment can significantly reduce I/O operations, thereby improving app startup time and responsiveness. zipalign is a crucial step in the build process for Android applications before they are distributed. It ensures that applications adhere to platform best practices, allowing for optimal performance and reduced resource consumption.

Using zipalign is usually performed as the last step before signing the .apk file.

zipalign modifies the zip archive in-place, so creating a backup of the original .apk file is recommended before running zipalign. An aligned file must be re-signed for it to be valid.

Always align *before* signing. Resigning an APK will break the alignment.

Commonly used to align resources and native libraries inside Android .apk files. It's used as a final step in building the app.

zipalign -v 4 myapp-unsigned.apk myapp-aligned.apk
This aligns the myapp-unsigned.apk archive with a 4-byte boundary and saves the aligned version to myapp-aligned.apk with verbose output.

zipalign was developed by Google as part of the Android SDK build tools. Its primary purpose is to optimize Android application packages (.apk files) for memory and performance by aligning uncompressed data. The tool became widely adopted as a standard step in the Android application build process, ensuring optimized application delivery and execution on Android devices.

jarsigner(1)