Today’s software applications require developers, testers, and SysAdmins to work together (DevOps) more seamlessly than ever before. A single line of code or poorly configured service can negatively impact your application’s performance, causing crippling slowdowns for end-users. This is where application performance monitoring (APM), comes in. APM is also referred to as application performance measurement or application performance management.

Regarding Linux server monitoring, monitoring critical performance metrics of Linux operating systems no matter the distro, helps SysAdmins keep tabs on their database servers, mail servers, caches, web/application servers and more. Including server OS health analysis, resources usage (disk i/o, memory, swap, CPU), network checks, Firewall/Security, MySQL performance, http servers (Apache, Nginx, etc), PHP (PHP-FPM, OpCache).

Almost two years ago I started to maintain a list of Top 100 Server Monitoring & Application Monitoring (APM) solutions. The list contains a BOTH free and paid Linux Server Monitoring and APM solutions. However, there’s a growing list of solutions which offer free accounts or that are completely free and open-source.

Instrumental: Free APM + Linux Server Monitoring.

Instrumental’s daemon automatically collects metrics for servers and services such as PHP, Nginx, MySQL, Memcached, MongoDB, PostgreSQL, Redis, Docker and others. Graphs are available for critical metrics that can be setup in just a few minutes. The Instrumental interface is designed with data exploration in mind. Allowing you to quickly dig into your application and server to find the root cause of issues. Free developer account includes up to 500 Metrics and 3 Hours of Data visibility.

Datadog: Modern monitoring and analytics.

Datadog is an infrastructure management service that’s ideal for IT shops that can fully leverage its automation, application programming interface (API), and data analysis capabilities. Datadog also offers many, many, integrations (350+), dashboards, and alerts that smaller companies will find useful. Free accounts include core collection and visualization, discussion group support, 1-day metric retention, up to 5 hosts.

Anturis: Server, application and network monitoring.

Anturis provides everything you need to monitor your Linux servers, web applications, networks and websites. You can setup up to 5 monitors + unlimited alerts with their Free account.

Nginx Amplify: Linux Server Monitoring + PHP-FPM and MySQL Free

Nginx Amplify is currently free, however I’ve been told that at some point they will introduce pricing. Nginx Amplify is a SaaS‑based monitoring tool for Nginx HTTP server. With NGINX Amplify you can monitor performance, keep track of infrastructure assets, and improve server configuration via analysis. Nginx Amplify also monitors the underlying OS, application servers (like PHP-FPM), databases (MySQL), and other components. The control panel alerts you of both performance and security related issues. For almost 2 years I’ve used it to keep tabs on Nginx and full page caching via fastcgi_cache. Enjoy it while it’s completely free!

Netdata: Get control of your servers. Simple. Effective. Free.

See whats happening on your systems and applications, with interactive web dashboards and performance/health alarms. Out of the box Netdata supports MySQL, Memcahced, Redis, Nginx and others. There are also a wide array of integrations (modules and plugins). Free and Open Source.

Munin: free and open-source Linux server monitoring

Munin is a system monitoring, network monitoring and infrastructure monitoring software application. This is a self-hosted solution for monitoring your Linux server, network and many other applications/services. Free and open-source.

…additional free options for Linux server monitoring/APM:

Last updated: June 26th 2018

AppDynamics – drops to a free plan after 15 day trial.

Cacti – free Open Source.

Collectd – free, Open Source project.

Goaccess.io – Open source http monitoring. (nginx, apache, etc)

Icinga – Open Source Monitoring.

Monit – free, Open Source software.

Monitorix – free, Open Source, very lightweight.

Nagios – You can download + install Nagios core for free.

New Relic – drops to a free plan after 14 day trial.

Prometheus – Free Open source. Self hosted.

Zabbix – Free Open Source. No limits or hidden costs

More… (Post suggestions in the comments section below)

Free Linux Server Monitoring Solutions will only get you so far…

Server monitoring and APM are essential to establishing and maintaining infrastructure which remains performant and operational. To monitor applications at code-level depth with minimal overhead, in real-time or within minutes, you’ll need to upgrade to paid solutions. (100+ Top Server Monitoring & Application Monitoring Tools).

It’s ok to start free, however, it may be best to select and combine solutions which offer premium options that fit within your budget as traffic, infrastructure and monitoring needs grow. For example, AppDynamics, Datadog, New Relic, Instrumental, etc allow you to eventually upgrade your account and/or purchase premium add-on services.

Disclaimer: AppDynamics, Datadog, and Instrumental are sponsors of this blog.