Difference Wiki

JAR vs. WAR: What's the Difference?

Edited by Janet White || By Harlon Moss || Published on February 6, 2024
JAR (Java Archive) is a file format for aggregating Java class files, while WAR (Web Application Archive) is used for distributing web applications.

Key Differences

JAR files are used to aggregate many Java class files, along with associated metadata and resources, into one file for efficient distribution and use. These files are commonly used for distributing Java libraries and applications. WAR files, on the other hand, are specifically used for web applications. They contain servlets, JSPs, HTML files, and other resources needed for web applications.
JAR files can contain any type of file but are primarily used for Java class files and application resources. They can be executed if they contain a main class. WAR files have a specific structure, including a WEB-INF directory that contains configuration files like web.xml. They cannot be executed independently like JAR files.
JAR files are versatile and can be used in various environments, from desktop applications to server-side applications. WAR files are specifically designed for deployment in a web server or application server environment. They are the standard for deploying Java-based web applications.
Both JAR and WAR files are based on the ZIP file format and can be opened using any ZIP file utility. However, the tools and utilities used to create and manage these files are often specific to Java development, like Maven or Gradle for JAR files and web-specific tools for WAR files.
In software development, JAR files are often used during the development of both standalone and web applications for packaging libraries. WAR files are used at the end of the web application development process, packaging the application for deployment on a server.

Comparison Chart

Primary Use

Aggregating Java class files and resources
Distributing web applications


Can contain any file type
Specific structure with WEB-INF directory


Can be executable
Not executable independently

Deployment Environment

Desktop, server-side applications
Web servers, application servers


General Java applications
Web applications (servlets, JSPs, HTML, etc.)

JAR and WAR Definitions


JAR files are often used for distributing software components in Java.
She downloaded a JAR file containing the latest version of the library.


WAR stands for Web Application Archive.
She deployed the WAR file to the application server.


JAR files can contain libraries, auxiliary resources, and executable classes.
He created a JAR file containing all the classes and images.


WAR files contain web-related content like JSPs, HTML, and servlets.
He updated the WAR file with new servlets and JSPs.


JAR can be executed if it includes a manifest specifying the main class.
He ran the application directly from the executable JAR file.


WAR files are deployed in web server environments.
After testing, the WAR file was uploaded to the production server.


JAR is a package file format used to aggregate Java class files.
The Java library was distributed as a JAR file.


WAR files have a specific directory structure including a WEB-INF folder.
He placed the configuration files in the WEB-INF directory of the WAR.


JAR stands for Java Archive.
They used a JAR file to deploy the Java application.


WAR is a file format used specifically for web application distribution.
The web application was packaged as a WAR file for deployment.


A cylindrical glass or earthenware vessel with a wide mouth and usually no handles.


A state of open, armed, often prolonged conflict carried on between nations, states, or parties.


What is a JAR file in Java?

A JAR file is a Java Archive format that aggregates many Java class files and associated resources.

What is the primary use of a WAR file?

A WAR file is used to package and distribute web applications.

How are WAR files structured?

WAR files have a specific structure, including a WEB-INF directory for configuration files.

Can I use a JAR file in a web application?

Yes, JAR files can be used as libraries within web applications.

Is a JAR file similar to a ZIP file?

Yes, JAR files are based on the ZIP file format.

Are JAR files used in mobile app development?

JAR files can be used in Android app development as library containers.

Can I convert a JAR to a WAR?

Converting a JAR to a WAR involves reorganizing its contents and structure to fit web application standards.

Can JAR files be executable?

Yes, JAR files can be executable if they contain a manifest file specifying a main class.

What servers are WAR files deployed on?

WAR files are typically deployed on web servers or application servers like Tomcat or JBoss.

Are JAR files only for Java applications?

Primarily, yes. JAR files are designed for Java applications and libraries.

What is a manifest file in a JAR?

A manifest file in a JAR specifies setup configurations, including the main class for executable JARs.

How do I create a JAR file?

JAR files can be created using Java development tools like Eclipse, IntelliJ, or build tools like Maven.

Is it possible to embed a JAR in a WAR?

Yes, JAR files can be included in the lib directory of a WAR for library dependencies.

Do WAR files include HTML and JavaScript?

Yes, WAR files can include HTML, JavaScript, JSPs, and more for web applications.

Can I open a JAR file with standard ZIP utilities?

Yes, JAR files can be opened with standard ZIP utilities.

Why would a developer choose a JAR file over a WAR?

A developer would choose a JAR file for general Java applications, especially when web-specific features are not needed.

Are there security concerns with JAR and WAR files?

Like any file format, JAR and WAR files can contain malicious code and should be sourced from trusted providers.

Do WAR files run independently?

No, WAR files need a web server or application server to run.

How are JAR files important in enterprise applications?

JAR files are crucial in enterprise applications for organizing and distributing Java libraries and components.

What's inside a WAR file's WEB-INF directory?

The WEB-INF directory contains configuration files, classes, and libraries specific to the web application.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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