PRTG Network Monitor is not available for Mac but there are plenty of alternatives that runs on macOS with similar functionality. The best Mac alternative is Netdata, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to PRTG Network Monitor and 16 are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to PRTG Network Monitor are CloudRadar Monitoring (Paid), Datadog (Paid), BitMeter OS (Free, Open Source) and NetCrunch (Paid).
Agentless monitor covers most of the aspects of monitoring like JAVA / J2EE application monitoring, server monitoring, database monitoring, transaction monitoring, network monitoring, log monitoring and system monitoring and last, but not the least is available for free.