A software called LeafMC has been growing in popularity recently and currently and most likely will never be available in our softwares so here is a tutorial on how to add LeafMC to your server!
Note: There may be a lot of errors and this does not guarantee that it will be added and LeafMC is mainly based on a mix of performance and vanlla and is a paper fork. Some plugins may not work yet, however check if they do work on purpur and if they do then report it to LeafMC GitHub not FMH: https://github.com/Winds-Studio/Leaf/issues/new/choose
First we will need the LeafMC server.jar file as this is what our server will be created based on, go to this page and download the recent version (when updating for LeafMC versions, you have to delete the current .jar file and then reupload the newest version). Head to this page and click download: https://www.leafmc.one/download
Once your file is downloaded, head to your files tab in the control panel and locate your current server.jar (it is recommended you remove all files and only keep server.properties). You will then need to upload the .jar file to your files tab, to do this either open your file manager and drag and drop the file or press upload and choose the .jar file.

Now the current way it is, the server will not start, this is because it looks for a file called "server.jar" to fix this we can do one of two things:
Rename the .jar file from leaf: To do this, right click on the .jar file or press the three dots on the right, select the first option which should say "Rename" and change the name to "server.jar".

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Or, change the file in the startup menu: The start up menu has an option called "SERVER JAR FILE" and this includes the server.jar name however this is editable. By changing the server.jar to the leaf.jar file name we can make the server start on that file.

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And that is it! Once you save all changes if prompted and start the server, you can play using LeafMC software!! If you get any errors in the console upon the first restart then remove the plugin-remapped file in the plugins directory. Remember you must remove all files before uploading your leaf.jar file except for server.properties!!
If you have any questions, then have a look in https://www.leafmc.one/docs/faq before going to FMH!!
(My leaf.jar is version 1.21.5 but this will work for new and older versions to!!)