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WAR (Web Application Archive) file format

.war  ·  package (ZIP variant)  ·  introduced 1999 by Sun Microsystems

What is a WAR (Web Application Archive) file?

A WAR file is a Java Web Application Archive: a ZIP file laid out with WEB-INF/, classes/, lib/, and a web.xml descriptor. Servlet containers like Tomcat and Jetty deploy WARs by simply dropping them into a webapps/ directory.

Most readers reach this page after double-clicking a .war file and finding their operating system unsure what to do with it. The good news: WAR (Web Application Archive) is a well-understood format with mature tooling on every major platform. It is supported in one click by mainstream archivers on Windows, macOS, and Linux.

How to extract a WAR (Web Application Archive) file

Opening a .war file is straightforward on every modern operating system. The exact steps depend on which platform you are on:

On Windows

  1. Locate the .war file in File Explorer.
  2. Right-click the file. If you have 7-Zip installed, choose 7-Zip → Extract Here. On Windows 11 the built-in extractor handles ZIP, 7z, RAR and several other formats directly through Extract All…
  3. If prompted, pick a destination folder and click Extract.
  4. The extracted files appear in a folder next to the original archive.

On macOS

  1. Find the .war file in Finder.
  2. Install The Unarchiver from the Mac App Store, or Keka for both creating and extracting.
  3. Right-click the file → Open With → The Unarchiver (or just double-click after Unarchiver is set as the default).
  4. The extracted folder appears next to the archive.

On Linux

  1. Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).
  2. On the command line, run one of: 
    7z x archive.war    # works for almost any format
  3. The files appear in the current directory.

How to create a WAR (Web Application Archive) file

To pack files into a .war archive, you typically need an archiver that supports writing this format. Not every tool can create every format — for example, only WinRAR can create real RAR files. The sidebar lists the software known to read and write WAR (Web Application Archive).

On the command line, the canonical create command is:

# Use 7-Zip, PeaZip, or the format's reference tool to create .war files.

If you regularly create archives at scale, a dedicated archive automation suite can wrap this command in scheduled jobs, integrity checks, and offsite replication.

Strengths

  • Standard servlet container deployment unit
  • Self-contained

Weaknesses and limitations

  • Java EE-specific
  • Modern Java prefers fat JARs and Spring Boot

Typical use cases

  • Tomcat / Jetty deployment
  • Java EE web modules

Technical details

WAR (Web Application Archive) uses the ZIP + WEB-INF/ algorithm and is identified on disk by the magic byte sequence 50 4B 03 04. The standard MIME type is application/java-archive. The format is an open specification and is free for any use.

Frequently asked questions

Is WAR (Web Application Archive) safe to open?

Archive files are containers — they are only as safe as what they contain. A .war from a trusted source is fine; one received from a stranger can hold malicious executables, scripts, or files engineered to exploit bugs in your archiver. Always keep your archiver updated, and never run unknown executables that come out of an archive. A safe workflow is to extract into a sandbox and scan the contents before opening anything.

What is the maximum file size?

Modern ZIP-based formats use the ZIP64 extension to support archives larger than 4 GB and individual files larger than 4 GB, up to 16 EB in theory. Older tooling that does not understand ZIP64 will report a corruption error on such files.

Can I password-protect a WAR (Web Application Archive)?

Some archivers can wrap WAR (Web Application Archive) files in an encrypted container, but the format itself does not always include built-in encryption. Check your archiver's documentation.

How does WAR (Web Application Archive) compare to other formats?

See our format comparison pages such as ZIP vs 7z, ZIP vs RAR, and tar.gz vs tar.xz for side-by-side feature tables.

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