Java / Kotlin Decompiler and AST Library
Branch: master
Clone or download


A java / kotlin decompilation tool and AST library.

The main goal of this library was to construct a complete Abstract Source Tree (AST) for a java class file including nodes for all instructions. It is built of top of ASM which has AST elements for methods but stops there and provides a simple opcode list.

While not as useful for modifying source and reconstruction a java class file this fill AST is very useful for decompiling and for code analysis where you would like to search for patterns on a statement rather than an opcode level.

For support and discussion see our Development/Support Chat on in the #decompiler channel.


At this time the kotlin support is quite new and all features are not set supported and bugs in the output are to be expected.

Usage as a Decompiler

java -jar Despector.jar <--config=[path]> <--lang=[java|kotlin]> [sources...] [destination]

  • The --config= allows you to define a config file for certain decompilation settings.
  • The --lang= forces the output to be in a particular language. Normal behaviour is to attempt to determine the class files source language from its contents.


This decompiler is still under heavy development and issues will happen. If you encounter any incorrect output please open an issue in the Issue Tracker. At a minimum include the expected and encountered output. A compiled class demonstrating the issue would also be extemely helpful.

Feature Requests

Feature requests are always welcome and can be made in the Issue Tracker with as much information as possible.

Configuration file

Here is a sample configuration file. It is optional but allows you to control decompilation settings such as formatting. If you would like more settings open a feature request in the Issue Tracker. The configuration file uses the HOCON configuration format.

# Despector decompiler configuration:

# Cleanup configuration
cleanup {
    # Cleanup operations to apply before emitting
# Targeted cleanup operations
# Emitter configuration
emitter {
    # Whether to emit synthetic members
    # The path of the formatter configuration
    # One of: eclipse,intellij
    # The path of the import order configuration
# Kotlin specific configuration
kotlin {
    # Whether to replace strings containing new lines with raw strings
# Prints out opcodes of a method when it fails to decompile.