What is a WAR file?
WAR — Java web application
What is it?
WAR is a specialized JAR: it packages a complete Java web application — pages, code, libraries, configuration — ready to be deployed on a server.
The administrator drops it into the designated directory, and the server installs it automatically. It is the standard delivery format for web applications in the Java ecosystem.
History & origin
The format was defined in the late 1990s alongside the first specifications for Java web applications, at a time when the web was becoming a platform for enterprise applications.
It remains widely used in large organizations, including banks and government agencies.
Why it is useful
Deployment is simple and repeatable: a single file, a single operation.
It enforces a standardized structure, which makes applications interchangeable across servers.
Limits & drawbacks
It only makes sense within a server-side Java environment.
For any other use, it is an inert file.
Practical tips
To inspect a WAR file, convert it to ZIP: its internal structure becomes readable.
Only deploy it on a server whose configuration you fully control — it is executable code.
Convert your WAR in seconds, on our secure servers in France.
Convert a WAR