Server JAR

The term ‘server jar’ refers to the startup file of a Minecraft server. Typically, this file name is server.jar and is located in the root directory of the server.

It is an executable file just like an exe, but it requires (correct version of) Java installed to run it. This file is typically run in the command line using a startup command, which starts the Minecraft server itself.

This file contains properties of the server, including its version, platform, support for plugins, and so on. Therefore, if you want to switch from Vanilla to the Paper platform, for example, you simply just replace the Vanilla ‘server jar’ with the Paper ‘server jar’. When you download a server platform, you are downloading the ‘server jar’ (to put it simply, the ‘server jar’ file is the Minecraft server itself - the executable file of the Minecraft server).