Better Vanish allows server admins or users with permission to go fully invisible to spectate/watch players.
It is based on the free public version on uMod by Wulf and has been in development since 2017.
However, this version was written from scratch with performance, security and optimization in mind.
Key features:
Vanished administrators cannot be seen by any other players or cheaters. ¹
Optimization with performance in mind. No garbage allocations.
Smaller size, lightweight with only most necessary functions for being invisible.
Auto-hide / Auto-noclip after joining. ²
Can be used by non-admins with certain restrictions.
Auto teleportation under the map or to a safe spot (if you crash or disconnect). ³
Vanished state persists between disconnects or server restarts (configurable).
Invisible to the world, environment, AI, traps and so on. ⁴
Custom & Lightweight trigger subsystem.
Vanished player is only enters the most important world triggers at zero overhead.
Can hide and unhide other players via command.
The inventory spy function will let you see and edit player's or NPC's inventories.
Sound effects when entering and leaving invisibility (other players can't hear it).
Supports original Vanish API & Hooks.
Explanations:
You must behave accurately if you don't want to get attention from potential cheaters. Do not play, shoot, or touch your inventory and outfit.
Auto-noclip is valid only for admins.
Non-admins cannot be teleported underground. Please use the safe points.
You still may provoke AI to follow you or shoot at you if you cause damage to them.