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
🌐
GitHub
github.com › FabricMC › intellij-fernflower
GitHub - FabricMC/intellij-fernflower: Fabric fork of fernflower, includes javadoc application, multithreading and a handful of fixes.
Fabric fork of fernflower, includes javadoc application, multithreading and a handful of fixes. - FabricMC/intellij-fernflower
Starred by 44 users
Forked by 12 users
Languages   Java
🌐
JetBrains
plugins.jetbrains.com › plugin › 8047-decompile-and-attach
Decompile and Attach - IntelliJ IDEs Plugin | Marketplace
GitHub | Issues | decompiles jar package using Intellij's build in Fernflower decompiler and attaches decompiled sources to project. the purpose is to have a...
🌐
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
🌐
GitHub
github.com › JetBrains › intellij-community › blob › master › plugins › java-decompiler › engine › src › org › jetbrains › java › decompiler › main › Fernflower.java
intellij-community/plugins/java-decompiler/engine/src/org/jetbrains/java/decompiler/main/Fernflower.java at master · JetBrains/intellij-community
public class Fernflower implements IDecompiledData { private final StructContext structContext; private final ClassesProcessor classProcessor; private final IMemberIdentifierRenamer helper; private final IdentifierConverter converter; ·
Author   JetBrains
🌐
JetBrains
blog.jetbrains.com › idea › tag › fernflower
Fernflower : The IntelliJ IDEA Blog | The JetBrains Blog
IntelliJ IDEA – the Leading IDE for Professional Development in Java and Kotlin · Follow · Follow: Linkedin Linkedin · Bluesky Bluesky · X X · Facebook Facebook · Youtube Youtube · RSS RSS Download · On October 20, the original author of the Fernflower Java decompiler, Stiver, passed away after a long fight against glioblastoma.
🌐
JetBrains
youtrack.jetbrains.com › issue › IDEA-175638 › Please-release-fernflower-decompiler-as-a-standalone-jar
Please release fernflower decompiler as a standalone jar
{{ (>_<) }} This version of your browser is not supported. Try upgrading to the latest stable version. Something went seriously wrong
🌐
Bytecode
the.bytecode.club › showthread.php
FernFlower - CLI Java Decompiler
Download, READ THIS! FernFlower has recently become open sourced, you can view the repo at https://github.com/JetBrains/intellij-co...decompiler If you're looking for GUI FernFlower, download Bytecode Viewer - https://github.com/Konloch/bytecode-viewer/releases Basic Decompile:
Find elsewhere
🌐
JetBrains
intellij-support.jetbrains.com › hc › en-us › community › posts › 360002822180-Fernflower-the-first-analytical-decompiler-what-does-that-mean-
Fernflower: the first analytical decompiler - what does that mean? – IDEs Support (IntelliJ Platform) | JetBrains
I'm not sure if this is the best place to ask this, but since as I understand it Fernflower is a part of InteliJ Idea. The readme (https://github.com/JetBrains/intellij-community/tree/master/plugins/java-decompiler/engine) says:
🌐
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 - Fortunately, the Fernflower decompiler that IntelliJ uses under the hood is Open Source and has a powerful command-line interface that can be used to decompile classes.
🌐
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
🌐
GitHub
github.com › fesh0r › fernflower
GitHub - fesh0r/fernflower: Unofficial mirror of FernFlower Java decompiler (All pulls should be submitted upstream)
Unofficial mirror of FernFlower Java decompiler (All pulls should be submitted upstream) - fesh0r/fernflower
Starred by 3.8K users
Forked by 699 users
Languages   Java
🌐
Maven Repository
mvnrepository.com › artifact › org.jetbrains › intellij-fernflower
Maven Repository: org.jetbrains » intellij-fernflower
Home » org.jetbrains » intellij-fernflower · IntelliJ Fernflower · Fabric (18) Central · Atlassian External · Atlassian · WSO2 Releases · WSO2 Public · Hortonworks · Mulesoft · JCenter · KtorEAP · Sonatype ·
🌐
JetBrains
blog.jetbrains.com › idea › 2024 › 11 › in-memory-of-stiver
In Memory of Stiver | The IntelliJ IDEA Blog
September 16, 2025 - In 2013, JetBrains approached Stiver with a suggestion to include Fernflower in IntelliJ IDEA. Part of the deal was making Fernflower open source. Everything went well, and the contract was signed. On July 11, 2014, the early access version of IntelliJ IDEA 14 was released, including the decompiler for the first time.
🌐
JetBrains
intellij-support.jetbrains.com › hc › en-us › community › posts › 360000897419-Intellij-decompiler-fernflower-decompiler-stopped-working-correctly-
Intellij decompiler (fernflower decompiler) stopped working correctly. – IDEs Support (IntelliJ Platform) | JetBrains
// Source code recreated from a .class file by IntelliJ IDEA · // (powered by Fernflower decompiler) and methods implementation, now it give me: // IntelliJ API Decompiler stub source generated from a class file // Implementation of methods is not available ·
🌐
GitHub
github.com › JetBrains › intellij-community › tree › master › plugins › java-decompiler › engine
intellij-community/plugins/java-decompiler/engine at master · JetBrains/intellij-community
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 ...
Author   JetBrains
🌐
GitHub
github.com › JetBrains › fernflower › blob › master › README.md
fernflower/README.md at master · JetBrains/fernflower
Decompiler from Java bytecode to Java, used in IntelliJ IDEA. - fernflower/README.md at master · JetBrains/fernflower
Author   JetBrains
🌐
YouTube
youtube.com › watch
How to create fernflower JAR and decompile Kotlin class to Java using a command line? - YouTube
fernflower is used internally by Intellij IDEA as a decompiler. If you have a use case to decompile Kotlin classes to Java using the command line, this video...
Published   April 21, 2021
🌐
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.