# Fernflower

Fernflower is a Malware Analysis product. It runs on-premises. Pricing is free.

Fernflower is an analytical decompiler for Java with command-line options and support for external classes.

Checked November 2026.

## What is Fernflower?

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

Tags: Binary Analysis

## Quick facts

- Category: [Security Operations](https://cybersectools.com/categories/security-operations) · [Malware Analysis](https://cybersectools.com/categories/malware-analysis)
- Deployment: On-Premises
- Company size fit: Startup, SMB, Mid-Market, Enterprise
- Pricing model: Free
- GitHub stars: 4,200
- Website: github.com

## Where it ranks

No shortlist covers this product's category yet. The closest is [Best MDR Solutions for Business](https://cybersectools.com/shortlists/best-mdr-solutions).

## Fernflower FAQ

### What is Fernflower?

Fernflower is a product in the Malware Analysis category. It covers Binary Analysis.

### What is the pricing for Fernflower?

Fernflower is free. Download and setup instructions are at https://github.com/JetBrains/fernflower.

### What are alternatives to Fernflower?

Alternatives to Fernflower listed on CybersecTools:

1. [ReversingLabs Spectra Analyze](https://cybersectools.com/tools/reversinglabs-spectra-analyze) - Malware analysis platform for SOC teams with binary analysis and threat detection (Commercial)
2. [Nightwing DejaVM](https://cybersectools.com/tools/nightwing-dejavm) - Whole-system emulation environment for software dev, debugging, testing & security (Commercial)
3. [Joe Sandbox DEC](https://cybersectools.com/tools/joe-sandbox-dec) - Plugin that decompiles malware PE files into readable C code using hybrid analysis. (Commercial)
4. [Zenyard RE Agent](https://cybersectools.com/tools/zenyard-re-agent) - AI agent for in-depth binary analysis and reverse engineering assistance. (Commercial)
5. [RevEng.AI](https://cybersectools.com/tools/revengai) - AI-powered binary analysis platform for reverse engineering & malware analysis. (Commercial)

Compare all Fernflower alternatives at [https://cybersectools.com/alternatives/fernflower](https://cybersectools.com/alternatives/fernflower)

### What deployment and organization size does Fernflower fit?

Fernflower is available as on-premises software. It is listed for startups, small businesses, mid-market companies and enterprises. It is free.

## Compare Fernflower with similar solutions

- [Fernflower vs ReversingLabs Spectra Analyze](https://cybersectools.com/compare/fernflower-vs-reversinglabs-spectra-analyze)
- [Fernflower vs Nightwing DejaVM](https://cybersectools.com/compare/fernflower-vs-nightwing-dejavm)
- [Fernflower vs Joe Sandbox DEC](https://cybersectools.com/compare/fernflower-vs-joe-sandbox-dec)

All alternatives to Fernflower: [/alternatives/fernflower](https://cybersectools.com/alternatives/fernflower)

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Source: https://cybersectools.com/tools/fernflower

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More on Fernflower: funding, momentum, hiring and news, plus the full product and company record, are available through the Mandos MCP Server (paid plans), which connects to AI assistants: https://mandos.io/mcp?utm_source=cybersectools.com&utm_medium=product-md