Modifying Android applications is a process that is often required by developers, testers, or enthusiasts who want to install two versions of the same app on one device. The stock Android system hard-codes installation to a unique identifier known as package name or Application ID. If you try to install a modified version of a game or utility with the same package name as the original, the system will either offer an update or throw a signature conflict error.
Changing the identifier allows you to bypass this limitation, turning the application into a completely new object for the operating system. However, this process is not limited to simply renaming the file; it requires deep intervention in the internal structure of the APK archive. AndroidManifest.xmlresources and code must be synchronized so that the application does not crash when launched.
In this article we will analyze in detail the technical aspects of changing the package name, consider the necessary tools and discuss the pitfalls that you may encounter when rebuilding. You will be working with decompiling code and editing configuration files, so attention to detail will be a key success factor.
Why change the application ID
The main reason why users resort to changing application ID, is the ability to clone apps. Imagine that you need to use two different accounts in one messenger or social network, but the developer did not provide a built-in multi-account function. By changing the package name of the modified version, you trick the system into thinking that it is a completely different app.
Developers also use this technique when forking projects. If you take the open source code of a popular application and want to release your own version with unique functionality, you absolutely cannot leave the old ID. Otherwise, users who already have the original installed will not be able to install your build, and updates will not arrive correctly.
⚠️ Warning: Changing the application ID may disrupt services that depend on the original developer signature. Push notifications, Google login, or license checks may no longer function after modification.
Another use case is testing. QA engineers often need to install a test build next to a production version to compare the behavior of features in real time. Without changing packageName this is technically impossible on one device without using special profiles or sandboxes.
Necessary tools for modifying APK
To successfully complete the task, you will need a set of specialized software. It is not possible to work with binary files directly in a text editor, since the code is compiled into Dalvik or ART bytecode. You will need decompilers that can convert classes.dex to readable smali or Java format.
The utility is considered the gold standard in the reverse engineering industry APKTool. It allows you to unzip the APK file, extract the assets and manifest, and then build the project back together. To edit code at a low level, it is often used JADX, which provides a convenient graphical interface for viewing decompiled Java code.
- 🛠️ APKTool - the main tool for unpacking and reassembling projects, working via the command line.
- 💻 Android Studio - necessary for signing the finished APK with a digital signature, since the Android system will not install an unsigned one package.
- 📝 Text editor —Notepad++, VS Code or any other editor that supports working with XML and large files without freezing is suitable.
In addition to the software, make sure that Java Development Kit (JDK)is installed on your computer. Most APK tools are written in Java and require the correct environment variables to run. Without the JDK, executing commands in the terminal will not be possible.
Use the version of APKTool that matches the version of your SDK Platform-tools. Incompatibility of versions can lead to errors when decoding resources of a new format.
Step-by-step guide for changing Package Name
The process of changing the package name requires a strict sequence of actions. Any deviation from the algorithm may cause the application to stop launching or to constantly close with an error. First, you need to decompile the source file to gain access to its internal structure.
Open a command line or terminal in the utility folder APKTool and enter the command to decode. After the process is completed, you will have a directory with the name of your application, containing all the resources, a manifest and a folder smali with code.
apktool d original_app.apk -o decoded_appThe next step is to edit the file AndroidManifest.xmllocated in the root of the unpacked folder. Find the attribute package in the top tag <manifest> and change it to a new unique value. It is usually built on the reverse domain principle, for example com.example.newapp.
☑️ Checklist for preparing for editing
However, simply changing the manifest is not enough. You need to rename the corresponding directories inside the folder smali. If your old package was com.old.name, and the new one com.new.name, you must physically move the smali files from the folder com/old/name to com/new/name, maintaining the nesting structure.
Editing code and paths in Smali
The most difficult part of the process is updating all references to the old package within the application code itself. In files of the smali format, paths to classes and resources are strictly written. If you change the folder structure, but do not update the imports and method calls within the code, the application crashes when trying to access a non-existent class.
Use the Find and Replace function in your text editor to bulk replace the old package prefix with the new one in all files in the directory. smali. Be extremely careful: replace only paths related to the package structure, and do not touch string literals that may accidentally be the same as the package name, but used in the interface.
| File type | What to change | Risk of error |
|---|---|---|
| AndroidManifest.xml | Package attribute in the manifest tag | Low (critical for installation) |
| Smali files | Class paths (Lcom/old/path/...) | High (leads to crashes) |
| Resources (R.java) | Links to resource identifiers | Medium (pictures/text do not work) |
Pay special attention to files that access external libraries or services. If there is a tight link within the code to the original package name for license verification or ad SDK setup, these sections of code will require manual analysis and possibly removal or modification of logic.
⚠️ Attention: When mass replacing text, make sure that you do not affect encrypted strings or service data that may contain sequences of characters that match the package name. This may violate the integrity of the encryption or the operating logic.
What to do if the application crashes after building?
Most often the problem lies in the fact that you forgot to rename the folders in the smali directory or did not update the paths inside the smali files themselves. Check the logs via adb logcat to find the name of the class that the system cannot find.
Reverse Build and Application Signing
Once all the files have been renamed and the links have been updated, you need to build the project back into an APK file. To do this, use the utility again APKTool, specifying the path to the folder with the modified files and the name of the output file.
apktool b decoded_app -o unsigned_app.apkThe resulting file will be unsigned. The Android operating system blocks the installation of such packages for security reasons. You need to generate a signing key and apply it to the file. To do this, you can use the utility jarsigner from the JDK or more modern tools like apksigner.
The signing process creates a cryptographic hash that confirms the authorship of the assembly. Even if you just changed the package name, the system will consider it a new application from a new developer, so a self-signed certificate is quite suitable for personal needs.
- 🔑 Create a keystore using the command
keytool. - ✍️ Sign the APK using the private key from the created store.
- ✅ Zipalign the file to optimize performance, although for modern versions of Android this is often done automatically during installation.
Possible problems and solutions
Even if you carefully follow the instructions, errors may occur. One of the most common problems is Conflict with another application. This occurs if an application with the same package name but a different signature is already installed on the device. The system prohibits replacing one application with another if they are signed with different keys.
To solve this problem, you must completely remove the original application before installing the modified version. If you want to keep both applications, make sure that the new one is unique and does not overlap with any installed package on the system. Another common mistake is without further explanation. This may indicate that your device's processor architecture is not compatible with the libraries inside the APK, or the file was corrupted during the rebuilding process. In such cases, analyzing the logs through package name is unique and does not overlap with any installed package on the system.
Another common mistake is App not installed without further explanation. This may indicate that your device's processor architecture is not compatible with the libraries inside the APK, or the file was corrupted during the rebuilding process. In such cases, log analysis via adb logcat.
Successfully changing the package name guarantees the isolation of the application from the original, but does not guarantee the functionality of all its functions, especially those that depend on server validation.
⚠️ Attention: Interfaces of developer tools and application store requirements are regularly updated. What worked in one version of Android may be blocked in another at the system kernel level. Always check the compatibility of modified APKs with your version of OS.
FAQ: Frequently asked questions
Is it possible to change the package name without a computer?
There are mobile APK editor applications such as MT Manager or NP Manager, which allow you to perform these operations directly on your smartphone. They have built-in functions for renaming the package and automatic rebuilding, which greatly simplifies the process for users without a PC.
Does changing the package affect receiving updates?
Yes, it does dramatically. A modified app with a new package name will not be able to update via Google Play or the original app store. You will have to manually download new versions of mods and install them over the old ones, since this is a completely different application for the system.
Is it safe to install such applications?
Safety depends on the source of the modification. Because you change the application's signature, the system cannot guarantee its integrity. If you modify the APK yourself, the risk is minimal. If you download a ready-made clone from an unverified source, there is a risk of introducing malicious code.
Why does the application crash immediately after launch?
The most likely reason is that not all links to the old package have been updated in the smali code. It is also possible that the application checks its own integrity or the package name on the server, and if a discrepancy is detected, it is forced to close.
Do you need to change the package name for system applications?
It is highly not recommended to change system application packages. This can lead to operating system instability, data loss, or even a bootloop. System processes are closely interconnected, and breaking these connections is fraught with serious consequences.