The best Network Analyzer alternative to NetAlertX is Nmap, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 10 alternatives to NetAlertX and nine of them are Network Analyzers so hopefully you can find a suitable replacement. Other interesting Network Analyzer alternatives to NetAlertX are Angry IP Scanner, Fing, Domotz and NETworkManager by BornToBeRoot.
NetAlertX alternatives are mainly Network Analyzers, but if you're looking for
Network Monitors or IP Scanners you can filter on that. These are just examples - use the filter bar below to find more specific alternatives to NetAlertX.