If you are someone who is into Android custom ROMs, then you would have heard the terms ‘Odexed’ and ‘Deodexed’. In this guide, we have explained all you need to know about Odexed and Deodexed and the differences between them.

Odex – What does Odexed mean in Android?

Odex, in Android, is short for “Optimized Dalvik Executable File” and is used to optimize the speed of apps in the Android system. Stock Android usually comes Odexed, which means there will be files with .odex extension within the system app folders. If you go to the /system/app folder on your Android, you will find a .odex file with every .apk file. For example, there will be a Calendar.apk and also a Calendar.odex file as well.

What does Odex file do in Android?

Odex file stores the metadata about an app such as startup parameters, app usage, etc. As the Odex files are stored separately from the actual APK file, Android’s dalvik virtual machine can compile it without having to decompile the APK file to get the information it needs. Odex files are directly loaded by the dalvik cache which makes the boot faster. And that is the reason why developers ask to wipe the dalvik cache while flashing a new ROM.

Deodex – What does Deodexed mean in Android?

Deodexed ROM is exactly the opposite of an odexed ROM. In an Odexed ROM, the APK fileand ODEX file exist as a single entity. Odex files are kept inside the APK file and you will only have the .Odex file. Deodexing is the process of repacking the APK with its corresponding ‘.ODEX’ file such that the information contained in the odex file is placed inside the APK in the form of classes.dex file.

Odexed vs Deodexed ROM – Which one to choose?

It basically comes down to personal choice. We have listed the advantages of both Odexed and Deodexed below so that you can make an informed decision:

Advantages of Odexed ROMs:

• Odexed ROMs come with a .ODEX file for every .APK file. This .Odex file is used by the Dalvik virtual machine to boot Android faster. The point is, Odexed ROMs have faster startup times.
• Odexed APK files generally take up less space than their deodexed counterparts.

If you care a great deal about the (startup) speed of your device/apps, then you should go with Odexed ROMs.

Advantages of Deodexed ROMs:

• Deodexed ROMs come with .APK files without .ODEX files. This makes modifying the APK file relatively easier as .ODEX file is combined with the APK file and they exist as one file.
• Easier file handling. There is only one file for every app instead of two as in the case of Deodexed ROM.

If you want to modify or theme an app or ROM, then Deodexed ROM is the way to go. Odex files makes it difficult for the developer to theme or hack the app as certain information about the app has is kept in a separate file in the form of .odex file. As Deodexed ROMs don’t have this issue, you should be good.

So, what’s your choice? Odexed or Deodexed?