The Problem with Monitoring Tool Lists
Most "best monitoring tools" articles read like vendor press releases. Everything is described as "powerful," "easy to use," and "enterprise-ready," which tells you nothing about which one you should actually run at 2am when your API is returning 500s. Let me try a different approach: here's what each category of tool is actually good at, and which specific tools are worth your time.
Error Tracking: Sentry
For application-level error tracking, Sentry is the clear recommendation. It captures exceptions with full stack traces, groups related errors intelligently, shows you which errors are new vs. recurring, and integrates with most languages and frameworks. The free tier is generous enough for small projects, and the paid tiers are priced reasonably for what you get.
The main alternative is Rollbar, which is fine but doesn't offer much over Sentry. Datadog has error tracking but it's expensive and overkill unless you're already using Datadog for everything else. Just use Sentry.
Infrastructure Monitoring: Prometheus + Grafana
If you're running your own infrastructure (VMs, containers, on-prem servers), the Prometheus and Grafana combination is the standard for a reason. Prometheus scrapes metrics from your services and stores them as time-series data. Grafana visualizes it with dashboards you can actually understand. Both are open source, and the community has pre-built dashboards for nearly everything you'd want to monitor.
The setup takes a few hours to do properly, but once it's running, it's incredibly durable. You can monitor CPU, memory, disk I/O, network traffic, database query times, custom application metrics — anything you can expose as a Prometheus endpoint.
For teams that don't want to self-host, Grafana Cloud has a free tier and managed Prometheus.
Uptime Monitoring: Better Uptime or Uptime Robot
These tools do one thing: check that your endpoints are responding and alert you when they're not. Better Uptime is the current recommendation — it has clean status pages, good alerting (email, Slack, PagerDuty), and incident management built in. Uptime Robot's free tier is hard to beat if you just need basic HTTP checks.
Don't skip uptime monitoring because you think your other tools cover it. They don't — at least not in a way that pages you immediately when your homepage returns a 503.
Log Management: Loki or Papertrail
Logs are what you read when metrics tell you something is wrong but don't tell you why. Grafana Loki integrates naturally with a Prometheus/Grafana stack and is cost-effective for high log volumes since it indexes labels rather than full text. Papertrail is simpler and works well for smaller teams that just want logs searchable without setting up infrastructure.
Elasticsearch/Logstash/Kibana (ELK) is the enterprise standard but has significant operational overhead — don't reach for it unless you have someone whose job is running it.
APM (Application Performance Monitoring): Datadog or New Relic
If you need full distributed tracing — following a request across microservices, identifying slow database queries, seeing exactly where latency is coming from — you're looking at proper APM. Datadog and New Relic both do this well. They're both expensive. If you're a startup, OpenTelemetry with Jaeger or Zipkin is the open-source path.
The Realistic Stack for Most Teams
You don't need all of this. A pragmatic monitoring stack for most production apps: Sentry for errors, Better Uptime for availability, and Prometheus/Grafana for infrastructure metrics if you're self-hosting. That covers the 90% case without drowning in dashboards. Add APM later if you start having performance problems that the basic stack can't explain.