Hi,
I’ve published a simple open-source tool to monitor LVARs.
Feel free to give it a try: GitHub - Clamb94/MSFSVariableWatcher
Edit: Or does something like this already exist? At least, I couldn’t find anything with live-update and search functionality.
In Developers mode, the Behaviors debug tool has a tab which can be used to monitor and even change LVars in real time.
Indeed, thanks. Never noticed that window before.
I’ll keep my tool up nonetheless, as it has some convenient filters 
And it also has a good FILTER to help reduce display overload !
DevMode tool has filters as well.
If you want a suggestion for a feature I would like to have, which the official tool lacks, it’s the ability to CREATE new L: vars not already created by something else.
Does anyone know how to monitor O: and H: vars?
O vars are scoped to particular elements in the model behaviours and not for external use. You can view them in the model behaviour debugger. H events are HTML events. You receive them in a HTML instrument when they are triggered by overriding BaseInstrument.onInteractionEvent.
Thank you!