What Is a .jar File? .jar Format, MIME & How to Open

Quick facts

Extension.jar

File typeJava Archive

MIME typeapplication/java-archive

CategoryArchive

Charset—

CompressibleNo

Format familyjava

What is .jar

What is a .jar file?

A .jar file is a Java Archive — ZIP-based archive bundling Java classes and resources.

In the mime-db registry it maps to application/java-archive, and it is marked as non-compressible. When serving .jar over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to application/java-archive — and is delivered over HTTP via the Content-Type header.

How to open .jar files

Use Java or 7-Zip to open and edit .jar files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: application/java-archive

Common software that reads/writes .jar:

Java7-Zip

Relation chain

.jarextension of

format

javaserved as

mime type

application/java-archivesent via header

http header

Related extensions

Web Application Archive

.ear

EAR Archive

Related MIME types

application/java-archive

.jar .war .ear

Common uses

File distribution
Backup bundles
Software installation packages

How to edit .jar files

Open the file with Java, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .jar files

Create a new file and save it with the .jar extension, or export this format from Java.

Frequently asked questions

What programs can open .jar files?

Common options include Java, 7-Zip. You can also open many of these files with built-in viewers or a browser.

How do I create a .jar file?

Create a new file in any text editor or the app that owns the format and save it with the .jar extension.

What is the relationship between .jar and the application/java-archive MIME type?

application/java-archive is the media type identifier used for .jar files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-09-13

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