This NPC Definition Editor (NDE) is made by Emperor for servers above revision 614. It has a simple GUI included to input values into.
If you cannot get the bat running simply open the dist folder and double-click NDE.jar.
Once a definition has been made, it will save to \NDE\data\NPCs in a XML format.
Disclaimer: Even though we have screened the files, please note that RuneLocus does not claim ownership of any of these files. We cannot be held responsible for any errors that might occur when using the download.