Description
PRTG Network Monitor is Paessler’s agentless, sensor-based monitoring platform for networks, servers, and IT infrastructure, priced entirely by sensor count rather than device count or feature tier. A single free Freeware Edition covers up to 100 sensors, enough for roughly 10 to 20 devices, with no time limit and the platform’s full core feature set. Paid subscriptions scale from PRTG 500 up through PRTG 10000, each unlocking more sensors for larger environments, with every subscription including the latest version, new features, and email support. Since July 2024, Paessler has sold PRTG exclusively on a subscription basis, ending the perpetual license option it previously offered. Each device typically consumes 5 to 10 sensors depending on how many aspects (CPU load, disk space, port traffic) are being monitored, so sensor budgets can run out faster than a raw device count might suggest. Organizations monitoring more than 1,000 devices are directed to the separate PRTG Enterprise Monitor product. It suits IT teams and small businesses that want a single, agentless monitoring tool without buying separate modules for logs, APM, or synthetics.
Key Features
- Sensor-based monitoring — each sensor tracks one measured value, like CPU load, disk space, or port traffic.
- Agentless architecture — monitors devices without installing separate agent software on each one.
- Auto-discovery — scans a network and suggests sensors for newly found devices.
- Custom dashboards and maps — visualizes network health with configurable, real-time maps.
- Multi-channel alerting — sends notifications via email, SMS, push, and other channels when a sensor fails a threshold.
- Distributed monitoring — remote probes extend monitoring to multiple sites from one central installation.
- Free Freeware Edition — full core feature set at up to 100 sensors, with no time limit.
How It Works
After installing PRTG on a Windows server or using PRTG Hosted Monitor in the cloud, an auto-discovery scan finds devices on the network and suggests relevant sensors for each one, such as ping, SNMP traffic, or disk space checks. Each device typically needs 5 to 10 sensors to cover its key metrics, so sensor count grows with monitoring depth, not just device count. Once sensors are running, PRTG tracks values continuously and triggers alerts through email, SMS, or push notification when a threshold is crossed. Custom dashboards and network maps give a live visual overview, while distributed monitoring lets remote probes extend visibility to branch offices or client sites from one central PRTG installation. When sensor usage nears a plan’s limit, upgrading to a larger license adds capacity without requiring a new installation or losing existing configuration.
Technical Architecture & Overview
- Core Engine: Not AI-based; a sensor-based, agentless monitoring engine using SNMP, WMI, packet sniffing, and other protocols to check each configured metric on a schedule.
- Deployment: Installed on a Windows server (on-premises), or delivered as PRTG Hosted Monitor in the cloud; PRTG Enterprise Monitor available separately for environments over 1,000 devices.
- API Surface: HTTP API for pulling sensor data and automating configuration; PRTG Sensor Hub offers community-built custom sensors, scripts, and templates.
- Known Limits: One sensor per switch port and roughly 5 to 10 sensors per device means sensor budgets can be consumed faster than device count alone suggests; different license sizes cannot be combined on one PRTG server.
Pros & Cons
| Pros | Cons |
|---|---|
| Freeware Edition offers the full core feature set at up to 100 sensors, permanently free, not a time-limited trial | Sensor-based pricing can be confusing to budget for, since one device often consumes 5 to 10 sensors |
| Pricing is transparent and published directly on Paessler’s site across all five paid tiers | Perpetual licenses were discontinued in July 2024; PRTG is now subscription-only |
| Agentless architecture avoids installing separate monitoring software on every device | Different PRTG license sizes cannot be combined on a single server installation |
| Single platform covers network, server, and bandwidth monitoring without separate priced modules | Environments over 1,000 devices require moving to the separately sold PRTG Enterprise Monitor |
| 30-day free trial removes the 100-sensor cap entirely to test a larger deployment first | Deeper AI-style reasoning or anomaly prediction is not a documented feature; alerting is threshold-based rather than predictive |
Pricing
| Plan | Price |
|---|---|
| Freeware Edition | Free forever (up to 100 sensors, full core features) |
| PRTG 500 | $200/month billed annually (up to 500 sensors, ~50 devices) |
| PRTG 1000 | $358/month billed annually (up to 1,000 sensors, ~100 devices) |
Platform Availability
Windows (on-premises) | Cloud (PRTG Hosted Monitor) | iOS | Android
Best For
First-time network monitoring | Small-to-mid IT teams | Windows-heavy environments
Frequently Asked Questions
Is PRTG really free, or just a trial?
The Freeware Edition is genuinely free forever, covering up to 100 sensors with the platform’s full core feature set, according to Paessler’s own pricing page. The separate 30-day trial temporarily removes the sensor cap entirely.
How many sensors does one device typically need?
Paessler states that most devices need about 5 to 10 sensors to monitor key metrics like CPU load, disk space, and traffic, with one additional sensor per switch port.
Is PRTG still sold as a one-time purchase?
No. Paessler moved PRTG to subscription-only pricing starting July 1, 2024, ending the perpetual license and annual maintenance model it previously offered.
What happens if I need to monitor more than 1,000 devices?
Paessler recommends PRTG Enterprise Monitor, a separate product built for very large environments, once monitoring needs exceed roughly 1,000 devices or 10,000 sensors.
How does PRTG differ from Domotz?
PRTG prices by sensor count with a permanently free 100-sensor tier, while Domotz prices flatly by collector or by managed device with no sensor math involved, and includes an MCP Server for AI agent access at no extra cost.
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