JD-GUI 1.6.6 - Free Java Decompiler Download (Windows, Mac, Linux) 2026
JD-GUI is a free standalone Java decompiler GUI. Decompile .class, .jar, .war, .ear files to readable Java source code. Open-source, cross-platform. Latest version 1.6.6.JD-GUI — Free Java Decompiler Download (Windows, Mac, Linux)
JD-GUI is a free, open-source standalone graphical utility that displays Java source code from compiled .class files. Decompile JAR, WAR, EAR, and other Java archives. Created by Emmanuel Dupuy. Released under GPLv3.
⬇ Download JD-GUI 1.6.6What Is JD-GUI?
JD-GUI (Java Decompiler GUI) is a standalone graphical utility that displays Java source code reconstructed from compiled .class files. Created by Emmanuel Dupuy as part of the Java Decompiler project, JD-GUI has been the go-to Java decompiler tool for over a decade. It allows developers, security researchers, and students to inspect compiled Java applications without access to the original source code.
Released under the GPLv3 License as fully open-source software, JD-GUI is free for personal, educational, and commercial use. It runs on Windows, macOS, and Linux as a portable application — no installation required. Drop a .class or .jar file onto the window, and JD-GUI immediately reconstructs and displays the Java source code with syntax highlighting, ready for browsing and analysis.
JD-GUI Key Features
📂 Multi-Format Support
Decompiles CLASS, JAR, WAR, EAR, AAR, KAR, JMOD, and ZIP files in one tool.
🎨 Syntax Highlighting
Color-coded Java source display makes decompiled code as readable as original.
🌳 Tree View Navigation
Browse package hierarchy, classes, methods, and fields with instant navigation.
🖱 Drag and Drop
Drop class files, JARs, or even LOG files containing stack traces directly into the window.
🔍 Search Function
Find strings, method names, and code patterns across decompiled source.
💾 Save Source
Export decompiled code as .java files individually or save entire projects.
📱 Portable
Runs from any folder or USB drive. No installation, no registry entries.
🌐 Cross-Platform
Native versions for Windows, macOS, and Linux. Same features everywhere.
📋 Stack Trace Analysis
Drop a LOG file and JD-GUI displays the line of code referenced in Java stack traces.
🔓 Open Source (GPLv3)
Full source code on GitHub. Inspect, modify, contribute. No vendor lock-in.
⚡ Fast Decompilation
Optimized for speed. Decompiles large JAR files in seconds.
📝 No Editing
JD-GUI is a viewer and decompiler. To edit, save the source and use your IDE.
How to Use JD-GUI
Quick Start
- Download JD-GUI 1.6.6 from this page. Pick the right version for your OS — Windows .exe, macOS .app, or Linux .jar.
- Launch the application. JD-GUI is portable — no installation needed. Just unzip and run.
- Drag and drop a Java class file (or JAR archive) onto the JD-GUI window. Alternatively, use
File > Openfrom the menu. - Browse the decompiled source. The tree view on the left shows package structure. The main pane shows the Java source.
- Search the code with
Ctrl+Fto find specific strings or methods. - Save the source code via
File > Save Sourcefor individual files, orSave All Sourcesfor the whole project.
Decompiling a JAR File
- Drag the
.jarfile into JD-GUI's main window. - JD-GUI displays the JAR contents in the tree view — packages, classes, resources.
- Click any
.classentry to see its decompiled source in the main pane. - Browse the entire JAR's structure using the tree.
- Save individual files or use
File > Save All Sourcesto export the entire decompiled JAR as a directory of.javafiles.
Analyzing Stack Traces
One of JD-GUI's underused features: drop a log file with Java stack traces directly into the window, and JD-GUI will display the lines of code referenced in those traces. Useful for production debugging when you have logs but not source.
Supported File Types
| Extension | Description | Common Use |
|---|---|---|
.class | Compiled Java class | Individual Java compiled files |
.jar | Java Archive | Standard Java library/application packages |
.war | Web Application Archive | Java web applications (Tomcat, Jetty) |
.ear | Enterprise Application Archive | Java EE/Jakarta enterprise applications |
.aar | Android Archive | Android library modules |
.kar | Knowledge Archive | Apache Karaf bundle archives |
.jmod | Java Module File | Java 9+ module files |
.zip | ZIP Archive | Generic archives containing class files |
.log / .txt | Log/text files | Stack trace analysis |
Java Version Compatibility
JD-GUI's decompiler core (JD-Core) supports a wide range of Java compilers:
| Java Version | JDK | Decompilation Quality |
|---|---|---|
| Java 1.1 - 1.4 | JDK 1.1.8 - 1.4.2 | Excellent |
| Java 5 (with annotations, generics, enum) | JDK 1.5.0 | Excellent |
| Java 6, 7, 8 | JDK 1.6.0 - 1.8.0 | Excellent (most common use case) |
| Java 9, 10 | JDK 9.0.1 - 10.0.2 | Good (modules supported) |
| Java 11+ | JDK 11+ | Limited — newer features may not decompile cleanly |
| Java 17, 21 (modern) | JDK 17, 21 | Limited — sealed classes, records, patterns may have issues |
JD-Core also handles JRockit 90_150_06, Jikes 1.2.2, Eclipse Java Compiler, and Apache Harmony bytecode.
System Requirements
| Operating System | Windows 7+, macOS 10.15+, Linux (any modern distro) |
|---|---|
| Java Runtime | JRE 8+ (some versions of JD-GUI need OpenJDK 11+) |
| Memory (RAM) | 512 MB minimum, 1 GB+ recommended for large JARs |
| Disk Space | ~1.6 MB for the executable |
| Display | Any standard resolution |
| Internet | Not required (works fully offline) |
JD-GUI for Different Operating Systems
Windows
Download jd-gui-windows-1.6.6.zip. Extract to any folder. Run jd-gui.exe directly. The application is portable — no installation, no registry changes. Ideal for keeping on a USB drive for portable analysis work. Tested on Windows 7, 8, 10, and 11.
macOS
Download jd-gui-osx-1.6.6.tar. Extract to your Applications folder or anywhere. Double-click the JD-GUI.app to launch. Works on macOS 10.15 (Catalina) and newer. Note: on macOS Catalina+, you may need to right-click and select Open the first time due to Gatekeeper. Also installable via Homebrew Cask: brew install --cask jd-gui.
Linux
Download jd-gui-1.6.6.jar. Run with java -jar jd-gui-1.6.6.jar from any terminal. Available in major distribution repositories: Debian/Ubuntu (apt install jd-gui), Kali Linux (apt install jd-gui), Arch Linux (AUR), Fedora (manual install). Requires Java Runtime Environment 8 or higher.
Common Use Cases
Recovering Lost Source Code
You compiled a Java application years ago, lost the source code, but still have the JAR. JD-GUI can reconstruct the source from the bytecode, getting you back to a workable starting point. This is one of the most legitimate and common use cases.
Inspecting Third-Party Libraries
You're using a Java library and need to understand exactly what a method does. The JavaDoc is incomplete or wrong. Drop the library JAR into JD-GUI to read the actual implementation. Useful for debugging integration issues.
Security Research and Vulnerability Analysis
Security researchers analyze proprietary or open-source Java applications for vulnerabilities. JD-GUI lets you read what an application actually does at the bytecode level. Pen-testers use this routinely on Java web applications (WAR files), Android apps (after extracting class files), and enterprise software.
Educational Study
Students learning Java often benefit from seeing how their code compiles. Compile your code, then decompile with JD-GUI to see how the Java compiler transforms your source. Eye-opening for understanding generics erasure, lambda compilation, and inner class implementation.
Debugging Production Issues
Production server throwing exceptions in code you don't have source for? Drop the JAR into JD-GUI, find the line referenced in the stack trace, understand what's happening. Drop the log file directly into JD-GUI and it links stack traces to source automatically.
Reverse Engineering Legacy Code
Inheriting an old Java application without source documentation. JD-GUI helps you understand the existing codebase before rewriting or extending it. Especially useful for proprietary applications that were never properly version-controlled.
JD-GUI vs Alternative Java Decompilers
| Decompiler | Strengths | Weaknesses |
|---|---|---|
| JD-GUI | Simple GUI, fast, portable, multi-format | Weaker on Java 11+ features |
| CFR | Strong modern Java support, command-line | No GUI by default |
| Fernflower | Used by IntelliJ IDEA, accurate | Slower, requires setup |
| Procyon | Good Java 5-8 decompilation | Less active development |
| Krakatau | Advanced bytecode analysis | Steep learning curve |
| DJ Java Decompiler | Older Windows-only tool | Less accurate, dated |
| JADX | Excellent for Android (DEX) | Android-focused, not general Java |
Many Java developers and security researchers use multiple decompilers in their workflow. When JD-GUI struggles with complex bytecode, switching to CFR or Fernflower often produces cleaner results. JD-GUI's simplicity makes it the natural starting point — quickly drop a JAR, see what's there, and switch tools only if the output is unclear.
Java Decompiler Project Components
JD-GUI is one of several tools in the Java Decompiler ecosystem:
JD-GUI
Standalone graphical utility. The most-used component. Drop files, browse decompiled code.
JD-Eclipse
Eclipse plugin. Integrates Java decompilation directly into Eclipse — see source even when you don't have it.
JD-Core
The underlying decompilation library. Used by both JD-GUI and JD-Eclipse. Available for embedding in other tools.
JD-IntelliJ
IntelliJ IDEA plugin (community-maintained). Similar functionality to JD-Eclipse for JetBrains users.
Tips for Effective Use
- Start with the manifest. Look at
META-INF/MANIFEST.MFfirst to understand JAR structure, dependencies, and main class. - Use the search function. For large JARs, searching for specific method names or strings is faster than browsing manually.
- Save before extensive analysis. Save the entire decompiled source so you can use grep, IDE features, and external tools alongside JD-GUI.
- Check JD-GUI vs CFR for confusing code. If JD-GUI output looks weird, decompile the same JAR with CFR — different tools handle obfuscated code differently.
- Open multiple JARs at once. JD-GUI can have multiple files open simultaneously. Use this to compare implementations across versions.
- Use stack traces directly. Drop a Java exception log file in to navigate from stack frames to source instantly — often faster than manual searching.
- For Android, use JADX first. Android APK files contain DEX bytecode that JD-GUI can't read directly. Use JADX to convert APK to JAR, then JD-GUI for further analysis.
Legal and Ethical Use
JD-GUI itself is legal — it's an open-source tool used legitimately by millions of developers. However, decompiling software is governed by copyright, software licensing, and reverse engineering laws that vary by jurisdiction.
Generally Acceptable Uses
- Recovering your own source code — your code, your right
- Open-source software study — already free to read
- Educational research — academic study of compilation techniques
- Security research with authorization — pen-testing software you've been authorized to test
- Interoperability analysis — many jurisdictions explicitly permit this
- Debugging your own production systems — analyzing software you own and operate
Potentially Problematic Uses
- Decompiling commercial software you don't own to copy or redistribute its code
- Bypassing license enforcement in commercial products
- Violating EULAs that specifically prohibit reverse engineering
- Stealing proprietary algorithms for competitive use
Always check the license of the software you're decompiling. Open-source projects usually permit it. Proprietary commercial software typically prohibits it in their EULA. When in doubt, consult legal counsel or use only for personal learning purposes.
Frequently Asked Questions
What is JD-GUI?
A free, open-source standalone graphical utility that displays Java source code from compiled .class files. Created by Emmanuel Dupuy. Supports CLASS, JAR, WAR, EAR, AAR, KAR, JMOD, and ZIP files. Released under GPLv3.
Is JD-GUI free?
Yes, completely free and open-source under GPLv3. No premium tiers, no commercial restrictions for personal or educational use. Source code on GitHub at java-decompiler/jd-gui.
What file types can JD-GUI decompile?
CLASS, JAR, WAR, EAR, AAR, KAR, JMOD, and ZIP files. Drag and drop any of these formats into the JD-GUI window for instant decompilation.
How do I use JD-GUI?
Download for your platform, launch (no install needed), drag a .class or .jar onto the window, browse the decompiled source in the tree view, search with Ctrl+F, save the source if needed.
What's the latest version of JD-GUI?
Version 1.6.6 is the current stable release. Includes JD-Core 1.1.3 with improved decompilation testing and recompilation accuracy.
Does JD-GUI work with modern Java (11, 17, 21)?
JD-GUI works well through Java 10. For Java 11+ features (sealed classes, records, patterns), decompilation may be incomplete. Consider CFR or Fernflower for modern Java work.
Is JD-GUI legal to use?
The tool itself is legal and widely used. Decompiling software depends on licensing — your own code or open-source software is fine; proprietary software typically prohibits it in EULAs. Check before decompiling.
Can I edit decompiled code in JD-GUI?
No — JD-GUI is a viewer/decompiler. Save the source code, then edit in your preferred IDE (Eclipse, IntelliJ, VS Code) and recompile with javac.
What are alternatives to JD-GUI?
CFR (strong modern Java support), Fernflower (used by IntelliJ), Procyon (Java 5-8 focus), Krakatau (advanced analysis), JADX (Android-focused). Many developers use multiple tools.
What are alternatives to JD-GUI?
Download JD-GUI 1.6.3 — Free Java Decompiler Download (Windows, Mac, Linux)
Software Information
| Software Name | JD-GUI (Java Decompiler GUI) |
|---|---|
| Also Known As | Java Decompiler GUI, JD GUI, jd-gui |
| Author | Emmanuel Dupuy |
| Project | Java Decompiler project |
| Category | Programming / Developer Tools / Decompilers |
| License | GNU GPL v3 (Open Source) |
| Latest Version | 1.6.6 |
| Operating Systems | Windows, macOS, Linux |
| File Size | ~1.6 MB |
| Java Requirement | JRE 8+ (or OpenJDK 11+ for some versions) |
| Source Code | github.com/java-decompiler/jd-gui |
| User Rating | 4.7/5 (1,542 reviews) |
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Software entry last updated: April 27, 2026.
Conclusion
To conclude JD-GUI 1.6.6 - Free Java Decompiler Download (Windows, Mac, Linux) 2026 works on Windows operating system(s) and can be easily downloaded using the below download link according to Freeware license. JD-GUI 1.6.6 - Free Java Decompiler Download (Windows, Mac, Linux) 2026 download file is only 1.6 MB in size.JD-GUI 1.6.6 - Free Java Decompiler Download (Windows, Mac, Linux) 2026 was filed under the Java and Javascript category and was reviewed in softlookup.com and receive 5/5 Score.
JD-GUI 1.6.6 - Free Java Decompiler Download (Windows, Mac, Linux) 2026 has been tested by our team against viruses, spyware, adware, trojan, backdoors and was found to be 100% clean. We will recheck JD-GUI 1.6.6 - Free Java Decompiler Download (Windows, Mac, Linux) 2026 when updated to assure that it remains clean.
JD-GUI 1.6.6 - Free Java Decompiler Download (Windows, Mac, Linux) 2026 user Review
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