Ender Chest Viewer tells you what someone has in the ender chest. through the use of a custom item called "ender viewer" or a custom command "/viewenderchest [player]"
join the discord: https://discord.gg/PG9egT2aKD
read before continueing:
Before i start seeing comments saying "the ender chest should be privite and you shouldn't be allowed to see the contents of other peoples ender chest". I created this addon because there is many time you do need to see the contents such as admins/mods cleaning up duped items. This addon allows them to be able to check for those duped items.
how to use:
there are 2 ways to use this addon, the 1st method is to look at your target then right click while holding the "ender viewer".

the 2nd method is to use a custom command "/viewenderchest [player]" which requires the person useing them to have operator permissions

no matter which method you use, it will send a message ingame that only you can see that says the contents of what is in their enderchest.
also this requres no experimental settings