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Paessler PRTG alternatives: 6 apps ranked by verified data

Facts checked Nov 1, 2026AppBreakup editorialHow we rank

Common reasons people leave Paessler PRTG: the core server runs only on Windows, and sensor-based licences get expensive as networks grow. We ranked 6 alternatives by how directly each one replaces Paessler PRTG, then by reviews, real visits and how recently each app's facts were checked against its own website. Datadog currently ranks first.

Quick comparison

#AppPricingOpen sourcePlatformsVerified factsScore
1Zabbix logoZabbixOpen sourceYesSelf-hosted, Linux, Web4 of 468.8
2Checkmk logoCheckmkFree plan + paidYesSelf-hosted, Linux, Web6 of 664.8
3Nagios logoNagiosOpen sourceYesSelf-hosted, Linux3 of 361.8
4Icinga logoIcingaOpen sourceYesSelf-hosted, Linux, Web3 of 359.4
  1. Zabbix logo

    1. ZabbixTop pick

    Best for: IT teams monitoring servers and network devices on-premises at scale without licence fees

    Open sourceSelf-hostableSelf-hosted, Linux, Web

    68.8

    score / 100

    Why switch from Paessler PRTG

    Free and open source with no sensor limits, and the server runs on Linux.

    Pros

    • Free with no per-device licence fees
    • Huge template library for devices and services
    • Scales to large estates with proxies

    Cons

    • Dense interface with a steep learning curve
    • Less suited to ephemeral containers
    • Self-hosting the database and server is on you
    Visit Zabbix Details and reviews
    How this score is calculated
    Editorial fit ×0.3100
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.15100
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Zabbix a good Paessler PRTG alternative?

    Verified facts

    4 of 4 verified
    License
    AGPL-3.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Licence change
    AGPLv3 from version 7.0
    Checked Oct 29, 2026zabbix.com(opens source in a new tab)
    Licence fees
    None
    Checked Oct 29, 2026zabbix.com(opens source in a new tab)
    Hosted option
    Zabbix Cloud
    Checked Oct 25, 2026zabbix.com(opens source in a new tab)
  2. Checkmk logo

    2. Checkmk

    Best for: IT teams with mixed server, network and cloud estates who want fast automatic setup

    Free plan + paidOpen sourceSelf-hostableSelf-hosted, Linux, Web

    64.8

    score / 100

    Why switch from Paessler PRTG

    Similar auto-discovery and ready-made checks, with a free open-source edition.

    Pros

    • Auto-discovery sets up checks with sensible thresholds
    • Rule-based web configuration
    • Free open-source community edition

    Cons

    • Best features are in paid editions
    • Rule system takes time to master
    • Server runs only on Linux
    Visit Checkmk Details and reviews
    How this score is calculated
    Editorial fit ×0.387
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.15100
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Checkmk a good Paessler PRTG alternative?

    Verified facts

    6 of 6 verified
    License
    GPL-2.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Free edition
    Checkmk Community
    Checked Oct 29, 2026checkmk.com(opens source in a new tab)
    SaaS option
    Checkmk Cloud
    Checked Oct 29, 2026checkmk.com(opens source in a new tab)
    Starting price
    From €190 a month, billed annually (Pro)
    Checked Nov 1, 2026checkmk.com(opens source in a new tab)
    Ultimate plan
    From €275 a month, billed annually
    Checked Nov 1, 2026checkmk.com(opens source in a new tab)
    Free plan
    Yes, Checkmk Community
    Checked Nov 1, 2026checkmk.com(opens source in a new tab)
  3. Nagios logo

    3. Nagios

    Best for: Admins who want a proven, plugin-based check engine for servers and networks

    Open sourceSelf-hostableSelf-hosted, Linux

    61.8

    score / 100

    Why switch from Paessler PRTG

    A long-standing open-source monitor with a huge plugin library for those happy to configure files.

    Pros

    • Enormous library of community check plugins
    • Stable and well understood after decades of use
    • Free open-source core

    Cons

    • Text-file configuration is laborious
    • Dated web interface
    • No built-in metrics storage or modern dashboards
    Visit Nagios Details and reviews
    How this score is calculated
    Editorial fit ×0.377
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.15100
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Nagios a good Paessler PRTG alternative?

    Verified facts

    3 of 3 verified
    License
    GPL-2.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Price
    Free and open source
    Checked Oct 29, 2026nagios.org(opens source in a new tab)
    Track record
    25+ years
    Checked Oct 29, 2026nagios.org(opens source in a new tab)
  4. Icinga logo

    4. Icinga

    Best for: Linux-savvy teams that want scriptable, distributed on-premises monitoring

    Open sourceSelf-hostableSelf-hosted, Linux, Web

    59.4

    score / 100

    Why switch from Paessler PRTG

    A modern open-source take on Nagios with a better web interface and an API.

    Pros

    • Compatible with Nagios check plugins
    • Clustering and REST API built in
    • Configuration works well with automation tools

    Cons

    • Requires solid Linux administration
    • Graphing needs extra components
    • Steeper setup than hosted tools
    Visit Icinga Details and reviews
    How this score is calculated
    Editorial fit ×0.369
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.15100
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Icinga a good Paessler PRTG alternative?

    Verified facts

    3 of 3 verified
    License
    GPL-3.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Free edition
    Forever free, open source
    Checked Oct 29, 2026icinga.com(opens source in a new tab)
    Open source
    Yes
    Checked Oct 29, 2026icinga.com(opens source in a new tab)

The best Paessler PRTG alternative for…

The highest-ranked app in this list for each need.

Datadog logo

Best Paessler PRTG alternative for most people

Datadog

A SaaS observability platform for teams also monitoring cloud apps, logs and traces.

Zabbix logo

Best Paessler PRTG alternative for a free option

Zabbix

Free and open source with no sensor limits, and the server runs on Linux.

Checkmk logo

Best Paessler PRTG alternative for a free plan you can upgrade

Checkmk

Similar auto-discovery and ready-made checks, with a free open-source edition.

Nagios logo

Best Paessler PRTG alternative for open source

Nagios

A long-standing open-source monitor with a huge plugin library for those happy to configure files.

Icinga logo

Best Paessler PRTG alternative for self-hosting

Icinga

A modern open-source take on Nagios with a better web interface and an API.

Zabbix logo

Best Paessler PRTG alternative for Linux

Zabbix

Free and open source with no sensor limits, and the server runs on Linux.

Site24x7 logo

Best Paessler PRTG alternative for iPhone and Android

Site24x7

A cloud-hosted option covering networks, servers and websites with no server to maintain.

Datadog logo

Best Paessler PRTG alternative for working in the browser

Datadog

A SaaS observability platform for teams also monitoring cloud apps, logs and traces.

Paessler PRTG alternatives: common questions

What is the best alternative to Paessler PRTG?

Datadog ranks first right now. A SaaS observability platform for teams also monitoring cloud apps, logs and traces. Zabbix and Checkmk follow it in our ranking.

Is there a free alternative to Paessler PRTG?

Yes. Datadog (free plan + paid), Zabbix (open source), Checkmk (free plan + paid) and Nagios (open source) have a free option. Check each app's verified facts for current plan limits.

Is there an open-source alternative to Paessler PRTG?

Yes: Zabbix, Checkmk, Nagios and Icinga. Zabbix, Checkmk and Nagios can also be self-hosted.

Which Paessler PRTG alternatives work on Linux?

Zabbix, Checkmk, Nagios and Icinga run on Linux.

Why do people switch from Paessler PRTG?

The complaints we hear most: the core server runs only on Windows; sensor-based licences get expensive as networks grow; different licence sizes can't be combined on one server.

How is this list ranked?

Every app is scored with the same published formula: how directly it replaces Paessler PRTG, reviews (weighted by verification), visits from AppBreakup, how recently its facts were checked against its own website, and reader votes.