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PRTG Network Monitor vs Cacti: catalog facts
PRTG Network Monitor	Cacti
Freemium Free for up to one hundred sensors. Larger deployments require a paid licence.	Free Free and open source under the GPL.
Windows, Web, Self-hosted	Linux, Web, Self-hosted
One hundred sensors free forever, which covers a small network Autodiscovery, maps and alerting configured through one interface	RRDtool storage keeps years of graphs in a fixed amount of disk Mature template and plugin ecosystem for network devices
Licensing is per sensor and gets expensive quickly Windows server only, closed source	Interface and workflow feel dated next to newer monitoring stacks Alerting requires plugins rather than being built in
Self-hosted	Self-hosted
Closed source	Open source
License not stated	License: GPL-2.0
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 22, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.