Unlike other emulators, in l2jdevs it is not necessary to modify the server core.
The core only contains the minimum necessary for the server to work. For all customizations and improvements, the data part is used. Everything is editable from the data, even what you want to modify from the core can be done from the data. In addition, it already has a mods and events engine.
Our core is totally private, hence its price. All our subscribers use the compiled version