Decompile a JAR in IntelliJ IDEA — or in 10 Seconds Without It

Step-by-step: open and decompile JAR files inside IntelliJ IDEA with the built-in Fernflower decompiler — or skip the IDE setup entirely and read any JAR's source in your browser.

How IntelliJ Decompiles JARs

Method 1: Add JAR as a Project Library

Method 2: Open the JAR Directly (Without a Project)

Navigation Tips for Decompiled JARs

Attach Source JARs (Better than Decompiling)

When to Use IntelliJ vs an Online Tool

IntelliJ's Decompiler Accuracy

FAQ