Fernflower
Fernflower is an analytical decompiler for Java with command-line options and support for external classes.
Fernflower is an analytical decompiler for Java with command-line options and support for external classes.
Checked October 2026.
Fernflower is the first actually working analytical decompiler for Java and probably for a high-level programming language in general. Naturally, it is still under development. Please send your bug reports and improvement suggestions to the issue tracker.
Fernflower is licensed under the Apache Licence Version 2.0. Running from the command line: java -jar fernflower.jar [-<option>=<value>]* [<source>]+ <destination>. * means 0 or more times, + means 1 or more times. <source>: file or directory with files to be decompiled.
Directories are recursively scanned. Allowed file extensions are class, zip, and jar. Sources prefixed with -e= mean 'library' files that won't be decompiled but taken into account when analyzing relationships between classes or methods. Especially renaming of identifiers (s. option 'ren') can benefit from information about external classes. <destination>: destination directory. <option>, <value>: a command-line option with the corresponding value (see 'Command-line options' below).
Examples: java -jar fernflower.jar -hes=0 -hdc=0 c:\Temp\binary\ -e=c:\Java\rt.jar c:\Temp\source\ java -jar fernflower.jar -dgs=1 c:\Temp\binary\library.jar c:\Temp\bin
No core features are listed for this product yet, so check the vendor's documentation for the full feature list.
No integrations are listed for this product yet. Check the vendor's documentation, or ask the vendor which integrations and APIs it supports.
Common questions about Fernflower: features, pricing and alternatives.
Fernflower is a product in the Malware Analysis category. It covers Binary Analysis.
Fernflower is free. Download and setup instructions are at https://github.com/JetBrains/fernflower.
Alternatives to Fernflower listed on CybersecTools:
Compare all Fernflower alternatives at https://cybersectools.com/alternatives/fernflower
Fernflower is available as on-premises software. It is listed for startups, small businesses, mid-market companies and enterprises. It is free.
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