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