client.jar

client.jar is a JAR file containing the Minecraft program and some default resources. It is launched by the user using the Minecraft Launcher.

The client.jar file is named using the version number after download, e.g., 1.21.5.jar. The name client.jar is used on the distribution server, and commonly as a general term for all versions of the file. It is located at .minecraft/versions/version/version.jar, next to the client.json file.

It can be opened with a file archiving program that supports ZIP files.