Try to invoke main class org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler manually

java -cp java-decompiler.jar org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler myclassfile.class .

Also you can find more about internal usage of Fernflower inside IDEA by query in source code https://github.com/JetBrains/intellij-community/search?utf8=%E2%9C%93&q=Fernflower

Answer from qwazer on Stack Overflow
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GitHub
github.com › JetBrains › fernflower
GitHub - JetBrains/fernflower: Decompiler from Java bytecode to Java, used in IntelliJ IDEA.
Decompiler from Java bytecode to Java, used in IntelliJ IDEA. - JetBrains/fernflower
Starred by 4.1K users
Forked by 715 users
Languages   Java
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Bytecode
the.bytecode.club › showthread.php
FernFlower - CLI Java Decompiler
java -jar fernflower.jar jarToDecompile.jar decomp/ With that fernflower will decompile jarToDecompile.jar and put the Java files into decomp/jarToDecompile.jar (Remember, jar is simply a .zip archive, so open it with any zip reader) If you run into the issue with people obfuscating as aa aA and you can't reobfuscate for some reason, fernflower has a neat ability that allows you to rename all of the classes/fields/methods to class1, class2, etc.
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GitHub
github.com › fesh0r › fernflower
GitHub - fesh0r/fernflower: Unofficial mirror of FernFlower Java decompiler (All pulls should be submitted upstream)
A decompiler from Java bytecode to Java. 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.
Starred by 3.8K users
Forked by 699 users
Languages   Java
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SoftTeco
softteco.com › home › java development › fernflower java decompiler
Fernflower Java Decompiler
July 3, 2025 - Fernflower is a really nice Java decompiler. It’s pretty convenient since you can decompile the whole JAR file.
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GitHub
github.com › 6168218c › FernflowerUI
GitHub - 6168218c/FernflowerUI: The fernflower decompiler with GUI.
The fernflower decompiler with GUI. Contribute to 6168218c/FernflowerUI development by creating an account on GitHub.
Starred by 109 users
Forked by 21 users
Languages   C++ 82.6% | C 17.4%
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YouTube
youtube.com › wernerware
Fernflower Decompiler for Java - YouTube
Use Fernflower to decompile java code from .class and .jar files. This video shows you how to do it without IntelliJ Video notes: https://github.com/wernerwa...
Published   June 16, 2018
Views   5K
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Eclipse Marketplace
marketplace.eclipse.org › free-tagging › fernflower
fernflower | Eclipse Plugins, Bundles and Products - Eclipse Marketplace | Eclipse Foundation
Enhanced Class Decompiler integrates CFR, FernFlower, JD, Procyon, Vineflower seamlessly with Eclipse and allows Java developers to debug class files without source code directly...
Find elsewhere
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GitHub
github.com › Vineflower › vineflower
GitHub - Vineflower/vineflower: Modern Java decompiler aiming to be as accurate as possible, with an emphasis on output quality. Fork of the Fernflower decompiler.
Modern Java decompiler aiming to be as accurate as possible, with an emphasis on output quality. Fork of the Fernflower decompiler. - Vineflower/vineflower
Starred by 1.8K users
Forked by 116 users
Languages   Java
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Maven Repository
mvnrepository.com › artifact › org.jboss.windup.decompiler › decompiler-fernflower › 2.3.0.Final
Maven Repository: org.jboss.windup.decompiler » decompiler-fernflower » 2.3.0.Final
Home » org.jboss.windup.decompiler » decompiler-fernflower » 2.3.0.Final · Windup Engine Decompiler Fernflower · Note: There is a new version for this artifact · Maven · Gradle · SBT · Mill · Ivy · Grape · Leiningen · Buildr · Scope: compile · test · provided ·
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JetBrains
youtrack.jetbrains.com › issue › IDEA-175638 › Please-release-fernflower-decompiler-as-a-standalone-jar
Please release fernflower decompiler as a standalone jar
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XDA Forums
xdaforums.com › home › asus › asus transformer tf700
[Tool][Decompiler] Fernflower | XDA Forums
November 17, 2012 - Hello, I would like to share this java decompiler with the community. FernFlower is the first analytic decompiler for java. It will decompile class files and jar files to human readable java code.
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GitHub
github.com › wux1an › fernflowers
GitHub - wux1an/fernflowers: Java ☕ reverse engineering tool - Batch decompile the jar package.
Java ☕ reverse engineering tool - Batch decompile the jar package. - wux1an/fernflowers
Starred by 10 users
Forked by 4 users
Languages   Java
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npm
npmjs.com › package › fernflower
fernflower - npm
Simple fernflower java decompiler wrapper. Latest version: 1.1.0, last published: 10 years ago. Start using fernflower in your project by running `npm i fernflower`. There are 1 other projects in the npm registry using fernflower.
      » npm install fernflower
    
Published   Apr 01, 2016
Version   1.1.0
Author   Romain Beaumont
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Microsoft
devblogs.microsoft.com › dev blogs › microsoft for java developers › java on visual studio code – july 2023
Java on Visual Studio Code - July 2023 - Microsoft for Java Developers
July 26, 2023 - Previously, users have reported that our extensions did not have good support of proper decompiling and debugging code. In our latest release, we have embedded a powerful Java decompiler called Fernflower (Currently an open-source project and used in IntelliJ IDEA) in our extension pack.
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JetBrains
blog.jetbrains.com › idea › 2024 › 11 › in-memory-of-stiver
In Memory of Stiver | The IntelliJ IDEA Blog
September 16, 2025 - Line numbers in decompiled code differ from line numbers in the original source, and Stiver helped provide a transparent mapping between them so you can seamlessly debug decompiled code. As Fernflower became open source, many other tools in the Java world used it – you can find a number of forks on GitHub.
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Reddit
reddit.com › r/java › new open source java decompiler
r/java on Reddit: New open source Java decompiler
April 29, 2022 -

Hello! Today I'm happy to announce the release of a project that me and my friends have been working on over the course of the last year, Quiltflower! Originally intended just for use with the QuiltMC toolchain with Minecraft, Quiltflower quickly expanded to be a general purpose java decompiler aiming to create code that is as accurate and clean as possible. If the name sounds familiar it's because Quiltflower is a fork of Fernflower, the (in)famous decompiler that was developed by Stiver, maintained by Jetbrains, and became the default decompiler in Intellij IDEA. Fernflower also quickly found its way into many other tools. After many frustrations with it myself with its decompiled code structuring and quality I decided to do something about it, and here we are! Over the past year, Quiltflower has added support for features such as modern string concatenation, a code formatter, sealed classes, pattern matching, switch expressions, try-with-resources, and more. Quiltflower also focuses on the code quality of the decompiled output, and takes readability very seriously. We'd greatly appreciate it if you'd give it a try, with our Intellij Plugin, as a standalone jar, or on our maven. While it has come a long way it's still a work in progress, and feedback can be reported on our issue tracker.

Here's a comparison of Fernflower and Quiltflower's output.

I'd also like to thank the MinecraftForge Team for creating ForgeFlower, the fork that QuiltFlower was based on, and Lee Benfield for creating CFR and it's truly incredible test suite.

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Jamie Tanna
jvt.me › posts › 2021 › 12 › 20 › java-decompile-command-line
Decompiling Java Class Files On the Command-Line · Jamie Tanna | Software Engineer
December 20, 2021 - It's incredibly convenient when ... decompiler that IntelliJ uses under the hood is Open Source and has a powerful command-line interface that can be used to decompile classes....