Freedom251 › Reverse Engineering Tools
Procyon
What Procyon is
Procyon is a free suite of Java metaprogramming tools for code generation and analysis. It includes reflection tools, expression trees, runtime code generation, and a Java decompiler. The reflection framework handles generics, wildcards, and other high-level Java type concepts, and includes TypeBuilder, MethodBuilder, and a bytecode emitter. Expression trees can be compiled into callbacks or paired with a MethodBuilder. The decompiler supports Java 5 and later features such as enums, switch statements, local classes, annotations, lambdas, and method references. Developers can integrate it through a public API, or use the standalone front end, which embeds dependencies in its JAR. Libraries are available from Maven Central under group ID org.bitbucket.mstrobel. The decompiler wiki says Java 7 is required to run it. The repository marks the compiler toolset and Java decompiler as experimental. It also cautions that classes built with Eclipse or compilers other than javac may produce less optimal results, particularly with String-based switch statements. Procyon displays an Apache-2.0 license.
Who it suits
Procyon suits developers working with Java reflection, code generation, expression trees, or decompilation. It may also suit developers who want to integrate decompiler functionality into an application through its public API.
What it does well
- Free suite of Java metaprogramming tools.
- Reflection supports generics and wildcards.
- Decompiler supports Java 5 and later features.
- Public API allows integration into other applications.
- Libraries are available from Maven Central.
What to know first
- Java 7 is required to run the decompiler.
- Compiler toolset and decompiler are marked experimental.
- Non-javac compiled classes may decompile less optimally.
Limits
The compiler toolset and Java decompiler are identified as experimental. Classes compiled with Eclipse or compilers other than javac may yield less optimal results, especially for String-based switch statements.
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Procyon | Java metaprogramming tools · libraries available from Maven Central | Free |
As github.com lists them, read 9 Oct 2026. The maker's own page has the final word.
Getting started
- Open the Procyon repository website.
- Use the Linux platform.
- Get Procyon libraries from Maven Central under group ID org.bitbucket.mstrobel.
- Use the standalone decompiler front end JAR, or integrate the framework through its public API.
- Run the decompiler with Java 7 or later.
Verdict
Procyon combines Java reflection, code-generation tools, expression trees, and decompilation in a free suite. Note the experimental status and the stated limitations with some non-javac compiled classes.
Questions
How much does Procyon cost?
The listed plan is free, and the pricing model is free.
Which platform is listed?
Linux is the listed platform.
Can Procyon decompile bytecode?
Yes. Bytecode decompilation is supported; native-code decompilation is not.
Can developers integrate Procyon into their applications?
Yes. The decompiler framework can be called programmatically through its public API.
What license does Procyon use?
The repository displays an Apache-2.0 license.
Does the decompiler support lambdas?
Yes. It supports Java 5 and later features including lambdas and method references.
Facts from Procyon's own pages
- Decompiler limitation
- Classes compiled with Eclipse or compilers other than javac may produce less optimal results, especially for String-based switch statements. · github.com, 9 Oct 2026
- Decompiler support
- The decompiler handles Java 5 and later features including enums, switch statements, local classes, annotations, lambdas, and method references. · github.com, 9 Oct 2026
- Distribution
- Procyon libraries are available from Maven Central under group ID org.bitbucket.mstrobel. · github.com, 9 Oct 2026
- Experimental components
- The compiler toolset and Java decompiler are identified as experimental in the repository README. · github.com, 9 Oct 2026
- Expression trees
- The expressions framework supports declarative expression trees that can be compiled into callbacks or coupled with a MethodBuilder. · github.com, 9 Oct 2026
- Interfaces
- The decompiler framework can be integrated into other applications and called programmatically through its public API. · github.com, 9 Oct 2026
- License
- The repository displays an Apache-2.0 license. · github.com, 9 Oct 2026
- Purpose
- Procyon is a suite of Java metaprogramming tools for code generation and analysis, including reflection, expression trees, and a Java decompiler. · github.com, 9 Oct 2026
- Reflection
- The reflection framework supports generics, wildcards, and other high-level Java type concepts. · github.com, 9 Oct 2026
- Related tools
- The repository lists SecureTeam Java Decompiler and Bytecode Viewer as third-party products based on or using Procyon. · github.com, 9 Oct 2026
- Runtime code generation
- The reflection framework includes TypeBuilder, MethodBuilder, and a bytecode emitter. · github.com, 9 Oct 2026
- Runtime requirement
- The Java decompiler wiki says Java 7 is required to run it. · github.com, 9 Oct 2026
- Standalone use
- The decompiler front-end embeds its dependencies in the JAR for easy redistribution. · github.com, 9 Oct 2026
Where Procyon stands on Freedom251
- Reverse Engineering Tools#40 of 73
- Decompiler Software#20 of 24