Netdata

Netdata is an open-source monitoring agent that provides real-time, per-second visibility into everything happening on a server. It auto-detects and monitors thousands of metrics out of the box: CPU, memory, disk I/O, network traffic, processes, systemd services, containers, web servers, databases, and hundreds of other applications and services.

What sets Netdata apart from traditional monitoring tools is its focus on real-time, high-resolution data. While most monitoring systems collect metrics every 15-60 seconds, Netdata collects per-second metrics by default. This granularity is invaluable for diagnosing performance issues that would be invisible at lower resolution, such as brief CPU spikes, momentary disk I/O saturation, or short-lived network latency spikes.

Installation is remarkably simple. A single bash command installs the agent, and it immediately starts collecting metrics from every detected service. There is no configuration required for most standard services. If MySQL, Nginx, Apache, PHP-FPM, Redis, or Docker is running, Netdata detects and monitors it automatically. The built-in web dashboard provides interactive, scrollable, zoomable charts for all collected metrics.

For hosting providers, Netdata is excellent for per-server monitoring. Install it on each server node and you get instant visibility into server health and performance. The alerting system includes hundreds of pre-configured alerts for common issues: high CPU usage, low disk space, memory pressure, service failures, and more. Alerts trigger through email, Slack, PagerDuty, and other notification channels.

Netdata Cloud (the freemium SaaS component) adds a centralized dashboard for viewing all your Netdata agents from one place, with role-based access control, custom dashboards, and alert management across your entire infrastructure. The free tier supports up to a small number of nodes, with paid plans for larger deployments.

Resource usage is surprisingly low despite the high-resolution data collection. The agent typically uses 1-3% CPU and 100-300MB of RAM, with configurable data retention periods. It stores data in a custom database engine optimized for time-series data on disk.