How to open a .jar file (Windows, Mac, Linux)

Q: Why can't I open my .jar file?

Usually your computer lacks an app that understands JAR. Install one of the apps listed here, or convert the file to a more common format.

A .jar file is a Java Archive. If double-clicking does nothing, your computer simply does not have an app that reads JAR yet. Here is how to fix that on each operating system, using free software wherever possible.

Open a .jar file step by step

Confirm the file really is a .jar. Drop it into the WhatFileType file identifier, which reads its signature without uploading anything.
On Windows, open it with Java Runtime (java -jar) or 7-Zip (to inspect).
On Mac, use Java Runtime (java -jar) or The Unarchiver.
On Linux, try Java Runtime (java -jar) or unzip.
Still stuck? Convert the .jar to zip, which opens more widely.

Best apps to open .jar files

Windows

Java Runtime (java -jar)
7-Zip (to inspect)
IntelliJ IDEA

macOS

Java Runtime (java -jar)
The Unarchiver
IntelliJ IDEA

Linux

Java Runtime (java -jar)
unzip
jar tool

Before you open it: Caution. A runnable JAR executes code. Only run JARs from sources you trust; inspecting one as a ZIP is safe.

Frequently asked questions

Why can't I open my .jar file?

Almost always because no installed app understands JAR. Install one of the apps above, or convert the file to a format your existing software already reads.

How do I open a JAR file?

To run it, use java -jar file.jar with Java installed. To look inside, rename it to .zip or open it in 7-Zip; it is a ZIP archive.

Why won't my JAR file run?

Usually Java is not installed, or the JAR has no main class in its manifest (it is a library, not an app). Install a Java runtime and check the JAR is executable.