Best Server Monitoring Tools: 11 Options Compared

You usually find out a server is in trouble in the worst possible way: a customer emails, the shop stops taking orders or the team can't log in. By then, the disk has been filling up for a week and nobody noticed.

Server monitoring tools are the early warning system. The eleven below are listed alphabetically and in no particular order, from free open source software you host yourself to cloud platforms you can switch on in minutes, and every description comes from the vendor's own site, read this week. If you're still choosing where your servers live, my explainer on what cloud hosting is and why it helps is a good starting point.

Server monitoring tools side by side

In the free plan column, Yes means the tool's own site names a free plan, a free edition or an open source version. Trial only means a time-limited trial. Not stated means the pages I read named neither, even where there's a button inviting you to try it or book a demo.

Tool	Type	Good for	Free plan
Better Stack	Monitoring, logs and incident management	Monitoring plus incidents and status pages	Not stated
Checkmk	Full-stack monitoring for hybrid IT	Mixed on-premises and cloud estates	Yes
Datadog	Infrastructure monitoring and observability	Cloud-heavy teams wanting one platform	Trial only
Nagios	Infrastructure monitoring	Long-established, self-hosted monitoring	Yes
Netdata	Real-time monitoring with built-in AI	Real-time metrics with little setup	Yes
New Relic	Full-stack observability platform	Observing servers, apps and AI together	Not stated
Prometheus	Open source metrics and alerting	Cloud-native stacks and custom metrics	Yes
Pulseway	RMM and IT management	Managing servers from anywhere	Not stated
Sematext	Server and infrastructure monitoring	Metrics and logs from one smaller vendor	Trial only
Site24x7	Cloud server performance monitoring	Server plus website monitoring together	Trial only
Zabbix	Open source observability	Large self-hosted monitoring set-ups	Yes

Eleven server monitoring tools to compare

Better Stack

Best for: Startups and small teams that want infrastructure monitoring, incident management and status pages from one modern platform.

Checkmk

Best for: IT teams with a mix of on-premises and cloud systems that want monitoring with a free, open source Community edition.

Datadog

Best for: Cloud-first engineering teams that want servers, containers and services monitored in one widely used observability platform.

Nagios

Best for: Sysadmins who want long-established infrastructure monitoring, starting with the free, open source Nagios Core.

Netdata

Best for: Teams that want real-time server metrics from an open source agent with self-learning anomaly detection built in.

New Relic

Best for: Engineering teams that want servers, applications and AI workloads observed together in one full-stack platform.

Prometheus

Best for: Engineering teams running cloud-native systems that want free, open source metrics collection and alerting they control.

Pulseway

Best for: IT admins and MSPs that want to watch and fix workstations, servers and network devices from anywhere they happen to be.

Sematext

Best for: Small DevOps teams that want server monitoring alongside logs and other observability tools from one smaller vendor.

Site24x7

Best for: Businesses that want cloud-based server performance monitoring next to website checks, with a 30-day free trial.

Zabbix

Best for: Organisations that want enterprise-class monitoring from open source software, with a managed cloud version as an option.

What server monitoring should cover

At a minimum: is the server up, and are CPU, memory and disk under control? A good tool also watches the services running on it, such as web servers and databases, tracks how quickly they respond and keeps a history so you can see slow trends, not just sudden failures.

Alerts matter as much as charts. You want the right person told about the right problem quickly, without being woken in the night for something that can wait until morning.

Check from the inside and the outside

The GOV.UK Service Manual tells government teams to set up internal and external monitoring checks, write monitoring checks and write alerts, and explains that internal monitoring is the monitoring you set up inside your own infrastructure.

That two-sided view is the part small businesses most often miss. A server can report that it's perfectly healthy while customers can't reach it because of a network or DNS problem. Pair agent-based checks on the machine with an outside check that visits your site or service like a customer would.

Servers talk through their logs, so pair this with log management tools.

Questions to ask before you choose

1. Do we need to install an agent on every server?
2. Which services and databases can you monitor out of the box?
3. How do alerts reach us, and can we set quiet hours or escalation?
4. How long is history kept, so we can spot slow trends?
5. Can you check our service from outside our network too?
6. Will it cope as we add servers, containers or cloud instances?

Fixing what you find is the job of configuration management tools.

Signs your servers need closer watching

• Customers report outages first. You hear about problems last.
• Disks fill up without warning. Services stop at random.
• Nobody can say what changed. There's no history to check.
• One person carries it all. Monitoring lives in their head.

Do you make server monitoring tools? Tool makers can ask to be considered for a featured place on this list.

My plain advice on choosing a server monitoring tool

Decide who'll answer the alerts before you choose the tool. If it's one busy person, a hosted service with sensible defaults beats a powerful system that needs weeks of tuning. If you've got an IT team that enjoys control, open source monitoring is hard to beat.

Start with a short list of checks that would have caught your last three incidents, then add more once the alerts feel trustworthy. Too many alerts teach people to ignore them. My guide to staying safe from cybersecurity threats covers the security side of keeping servers healthy.

Frequently asked questions

What is server monitoring?

It's the continuous checking of a server's health, such as CPU, memory, disk and services, with alerts when something goes wrong or drifts out of normal range.

Is there free server monitoring software?

Yes. Several well-known monitoring tools are open source and free to run yourself, and many hosted tools offer free trials.

What's the difference between server monitoring and uptime monitoring?

Uptime monitoring checks from outside whether a site responds. Server monitoring looks inside the machine at its resources and services.

Do I need an agent on each server?

Most detailed monitoring uses a small agent. Some checks can run without one, using standard protocols or outside checks.

How often should servers be checked?

It depends on the service. Critical systems usually warrant the shortest interval your tool allows, while less important checks can run less often.

Can server monitoring tools watch cloud servers?

Yes, most cover cloud instances and containers as well as physical servers, often with ready-made integrations.