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Best Free Alternatives to Paessler PRTG Network Monitor
Stop paying Free (100 Sensors) / ~$2,149/yr (500 Sensors). Discover professional-grade tools that won't break your budget.
Category: All-in-One Infrastructure MonitoringVerified for 2025
Top Recommended Replacements
Zabbix 7.0+
FREEBest Professional Free Alternative
Why we like it
100% free with no sensor or device limits; exceptionally scalable; the 2025/2026 builds feature native OpenTelemetry support and AI-driven trend analysis.
Keep in mind
Significant learning curve compared to PRTG; the UI is functional but lacks the 'one-click' simplicity of Paessler.
Observium Community
FREEBest for Network Visibility
Why we like it
Incredibly clean UI; exceptional auto-discovery for network hardware (Cisco, HP, etc.); the 'Professional' tier is very affordable for small businesses.
Keep in mind
The Community version has limited alerting capabilities; primarily focused on 'Network' rather than deep 'Application' monitoring.
Checkmk (Raw Edition)
FREEBest for High-Performance Scaling
Why we like it
Uses a high-performance monitoring core that is significantly faster than PRTG; handles thousands of checks per second with minimal CPU usage; very easy to automate.
Keep in mind
The Free 'Raw' edition lacks the commercial 'Micro Core' and the advanced reporting features of the Enterprise tier.
Cacti
FREEBest for Historical Graphing
Why we like it
The king of RRDTool-based graphing; excellent for tracking long-term trends in bandwidth and resource usage; completely free.
Keep in mind
The interface feels very dated (90s style); configuration is manual and tedious compared to modern auto-discovery tools.
Netdata
FREEBest for Real-Time Server Health
Why we like it
Provides per-second resolution for Linux/Unix servers; zero configuration needed for your aaPanel VPS; beautiful, modern real-time dashboards.
Keep in mind
Focused on 'Performance' rather than 'Network Management'; does not handle SNMP mapping for switches as well as PRTG.
Uptime Kuma
FREEBest for Website Uptime
Why we like it
Incredibly simple and beautiful; monitors HTTP(s), Ping, and DNS; features a built-in 'Status Page' for your users; perfect for a WordPress agency.
Keep in mind
Strictly an 'Uptime' monitor; lacks deep hardware or network traffic (NetFlow) analysis.
Site24x7
Best SaaS Alternative
Why we like it
Unified monitoring for websites, servers, and cloud; very affordable entry point; AI-powered anomaly detection helps spot trends early.
Keep in mind
SaaS only (data leaves your network); pricing based on 'monitors' can be confusing as your infrastructure grows.
LibreNMS
FREEBest for Multi-Vendor Hardware
Why we like it
Fully-featured network monitoring with excellent support for almost any hardware; includes a great mobile app and billing module for bandwidth.
Keep in mind
Requires a Linux environment to host; UI is clean but can be slower to load than PRTG's native Windows console.
Nagios Core
FREEThe Reliable Veteran
Why we like it
Thousands of community plugins available; rock-solid stability; you can monitor literally anything if you can write a script for it.
Keep in mind
Steep learning curve; configuration is primarily file-based; the 'Core' UI has not been modernized in years.
Auvik
Best for Network Mapping
Why we like it
Automated 2D/3D topology mapping that exceeds PRTG's capabilities; handles configuration backups natively; perfect for MSPs.
Keep in mind
No permanent free tier; pricing is based on the number of managed devices (switches/routers/firewalls).
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