donut 
(see yaπ)STOP! do you know what happened to defed.xyz?
Don't what it was?
This was a tool that made it easy to check de-federations a particular fedi instances has with respect to other instances. The site did this through basically sifting public blocklists and and moderated servers of a bunch of fediverse instances.
If you have any information about its whereabouts I would like to know since I'm not able to access it on my end.