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A java obfuscator (GUI)
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Obfuscator Build Status Join the chat at Donate

A Java bytecode obfuscator supporting

  • Flow Obfuscation
  • Line Number Removal
  • Number Obfuscation
  • Optimisation
  • Name Obfuscation (Classes, methods and fields) with custom dictionaries
  • Deobfuscator crasher
  • String Encryption
  • Inner Class Removal
  • HWID Locking
  • Invoke Dynamic
  • Reference Proxy
  • Member Shuffling & Hiding

Feel free to join my discord server: Discord Chat

Obfuscated code

Luyten + Procyon


public class HelloWorld {
    public HelloWorld() {
    public static void main(final String[] args) {
        System.out.println("Hello World");
        for (int i = 0; i < 10; ++i) {

Obfuscated (short version for full code visit

public class HelloWorld {
    public static void main(final String[] array) {
        // invokedynamic(1:(Ljava/io/PrintStream;Ljava/lang/String;)V, invokedynamic(0:()Ljava/io/PrintStream;), HelloWorld.llII[HelloWorld.lllI[0]])
        float lllllllIlIllIII = HelloWorld.lllI[0];
        while (llIll((int)lllllllIlIllIII, HelloWorld.lllI[1])) {
            // invokedynamic(2:(Ljava/io/PrintStream;I)V, invokedynamic(0:()Ljava/io/PrintStream;), lllllllIlIllIII)
            if (" ".length() == (" ".length() << ("   ".length() << " ".length()) & ~(" ".length() << ("   ".length() << " ".length())))) {
                throw null;


--help Prints the help page on the screen

--version Shows the version of the obfuscator

--jarIn <input> Input JAR

--jarOut <output> Output JAR

--config <configFile> Config File

--cp <classPath> Class Path

--scriptFile <scriptFile> A JS file to script certain parts of the obfuscation

--threads Sets the number of threads the obfuscator should use

--verbose Sets logging to verbose mode


java -jar obfuscator.jar --jarIn helloWorld.jar --jarOut helloWorld-obf.jar

java -jar obfuscator.jar --jarIn helloWorld.jar --jarOut helloWorld-obf.jar --config obfConfig

Example Config

  "input": "D:\\Computing\\HelloWorld\\out\\artifacts\\HelloWorld_jar\\HelloWorld.jar",
  "output": "D:\\Computing\\HelloWorld\\out\\artifacts\\HelloWorld_jar\\HelloWorld-obf.jar",
  "script": "function isRemappingEnabledForClass(node) {\n    return true;\n}\nfunction isObfuscatorEnabledForClass(node) {\n    return true;\n}",
  "libraries": [
    "C:\\Program Files\\Java\\jre1.8.0_211\\lib",
  "Crasher": {
    "Enabled": false,
    "Invalid Signatures": true,
    "Empty annotation spam": true
  "InvokeDynamic": {
    "Enabled": true
  "HWIDPRotection": {
    "Enabled": false,
    "HWID": ""
  "Optimizer": {
    "Enabled": true,
    "Replace String.equals()": true,
    "Replace String.equalsIgnoreCase()": true,
    "Optimize static string calls": true
  "LineNumberRemover": {
    "Enabled": true,
    "Rename local variables": true,
    "Remove Line Numbers": true,
    "Remove Debug Names": true,
    "Add Local Variables": true,
    "New SourceFile Name": ""
  "StringEncryption": {
    "Enabled": true,
    "HideStrings": true,
    "AES": true
  "NumberObfuscation": {
    "Enabled": true,
    "Extract to Array": true,
    "Obfuscate Zero": true,
    "Shift": false,
    "And": false,
    "Multiple Instructions": true
  "ReferenceProxy": {
    "Enabled": false
  "ShuffleMembers": {
    "Enabled": true
  "InnerClassRemover": {
    "Enabled": true,
    "Remap": true,
    "Remove Metadata": true
  "NameObfuscation": {
    "Enabled": true,
    "Excluded classes": "HelloWorld",
    "Excluded methods": "",
    "Excluded fields": ""
  "General Settings": {
    "Custom dictionary": true,
    "Name dictionary": "hello,world"
  "Packager": {
    "Enabled": false,
    "Use MainClass from the JAR manifest": true,
    "Main class": "HelloWorld"
  "FlowObfuscator": {
    "Enabled": true,
    "Mangle Comparisons": true,
    "Replace GOTO": true,
    "Replace If": true,
    "Bad POP": true,
    "Bad Concat": true,
    "Mangle Switches": false,
    "Mangle Return": false,
    "Mangle Local Variables": false
  "HideMembers": {
    "Enabled": true
  "Inlining": {
    "Enabled": false

Excluding Classes

In some situations you need to prevent certain classes from being obfuscated, such as dependencies packaged with your jar or mixins in a forge mod.

You will need to exclude in two places.

Scripting Tab

Here is an example script that will obfuscate and remap all classes except the org.json dependency and mixins.

function isRemappingEnabledForClass(node) {
    var flag1 = !"org/json");
    var flag2 = !"com/client/mixin");
    return flag1 && flag2;
function isObfuscatorEnabledForClass(node) {
    var flag1 = !"org/json");
    var flag2 = !"com/client/mixin");
    return flag1 && flag2;
Name Obfuscation

If you also want to exclude these classes from name obfuscation you will need to go to Transformers -> Name Obfuscation and add these exclusions there.

To Exclude the same classes as we did above, we would need to add the following to Excluded classes, methods and fields.


If your classes are still being obfuscated after applyinng both of these exclusions please open an issue.


1. Fork the repository
  • Click the "Fork" button at the top right hand corner of this page
  • Then run git clone[your github username]/obfuscator.git
2. Import into IntelliJ
  • File -> New -> Project From Existing Sources
  • Select C:\[Path To]\obfuscator\pom.xml
  • Set "Search for projects recursively" and "Import Maven projects automatically" to true and click next
  • Make sure all maven projects are ticked
  • Select the correct Java SDK and go with all the default options for the next pages
3. Editing
  • Make any edits
  • Package the project to make sure that the project is still functional:
    • java -Dmaven.multiModuleProjectDirectory=D:\Computing\obfuscator\obfuscator-core "-Dmaven.home=C:\Program Files\JetBrains\IntelliJ IDEA 2019.1.3\plugins\maven\lib\maven3" "-Dclassworlds.conf=C:\Program Files\JetBrains\IntelliJ IDEA 2019.1.3\plugins\maven\lib\maven3\bin\m2.conf" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.1.3\lib\idea_rt.jar=18889:C:\Program Files\JetBrains\IntelliJ IDEA 2019.1.3\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\JetBrains\IntelliJ IDEA 2019.1.3\plugins\maven\lib\maven3\boot\plexus-classworlds-2.5.2.jar" org.codehaus.classworlds.Launcher -Didea.version2019.1.3 package (Change any paths to be relevant to your system)
3. Commit
  • Run git status to see which files you've changed
  • Run git add [file name] for each of the files you want to submit your changes to
  • Do git commit -m "[A description of the changes]"
  • And finally git push to upload your changes to GitHub
4. Pull Request
  • Go to[your github username]/obfuscator and click "Pull Requests" and then "New Pull Request"
  • Make sure all your changes are included then submit the Pull Request.


  • MCInjector (FFixer base)
  • FFixer (Obfuscator base)
  • SmokeObfuscator (Some ideas)
  • MarcoMC (Some ideas)
  • ItzSomebody (NameUtils.crazyString(), Crasher)
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