"Sandfly is an automated security investigator that hunts for compromised Linux systems without having to install agents on your endpoints." https://www.sandflysecurity.com/
Magic? In the real world information is transmitted from one place to another. If monitoring of the information being received and sent by your computer isn't being done by your computer, then that monitoring is being done on some other computer with the information received by or sent from your computer being mirrored to that other computer.
Or does 'Hunt' mean a byte-wise examination of every file on your computer?
"5 Hosts free". So is this 50% discount coupon -- all you have to do is give me your name, date of birth and Social Security Number.
Who is doing the hunting/monitoring? Do you trust them? Do you have any reason to trust them?