Java Decompiler
Convert Java .class bytecode to readable Java source. Upload a .class file or paste hex. No server — runs entirely in your browser.
Drag & drop your .class file here
or click to browse
Accepts .class files only · Max 5 MB
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Frequently Asked Questions
Quick answers to common questions
Can this decompile any .class file?+
This tool can decompile most standard Java .class files and extract class structure, fields, method signatures, and bytecode. Complex obfuscated classes may show limited output. For production decompilation of obfuscated code, tools like CFR or Fernflower running locally are recommended.
Is my .class file uploaded to any server?+
No. Your .class file is processed entirely in your browser using JavaScript. Nothing is sent to any server. Your code stays completely private.
What Java versions are supported?+
Java 1 through Java 22 (class file versions 45–66) are supported. The tool detects the Java version automatically from the class file header.
What is a .class file?+
A .class file is compiled Java bytecode. When you compile Java source code with javac, it produces .class files containing platform-independent bytecode that runs on the Java Virtual Machine (JVM).
Can I decompile a JAR file?+
JAR files are ZIP archives containing multiple .class files. Extract the JAR first using any ZIP tool, then upload individual .class files here.
Why does the output look different from the original source?+
Decompilation is a reverse process — the original variable names, comments, and some code structure are lost during compilation to bytecode. The decompiled output is functionally equivalent but may use generated names.