Best Open Source Monitoring Tools in 2026
Ten tools you can run entirely on your own infrastructure, with no per-host bill and no vendor deciding what happens to your data.
Start with Prometheus for metrics and alerting, Grafana for dashboards, and Loki for logs if you want the standard self-hosted stack. Want traces, metrics, and logs in one UI instead of stitching three tools together? Pick SigNoz. Need a five-minute status page? Uptime Kuma runs in a single Docker container. All ten picks here are genuinely open source and self-hostable end to end, not source-available demos of a paid product.
Of the 10,000+ tools Toolradar tracks, these are the open-source monitoring and observability tools you can self-host end to end, with no SaaS bill, no per-host pricing, and no vendor deciding how long you get to keep your own metrics. That matters more than it sounds: Datadog and New Relic bill by host and by data volume, and both numbers only go up as your infrastructure grows. Self-hosting trades that recurring cost for your own compute and your own on-call rotation to keep the stack healthy.
We built this list by checking each tool's actual license file on GitHub in August 2026, not its marketing copy. A tool only made the cut if the core product is released under an OSI-recognized open source license (MIT, Apache 2.0, BSD, GPL, AGPL, MPL) and can be deployed on infrastructure you control, with no phone-home requirement to a vendor's cloud. That ruled out several strong products from our broader monitoring database: Datadog, New Relic, Better Stack, UptimeRobot, and StatusCake are closed-source SaaS, so they are covered separately in our best free monitoring tools guide instead. Sentry and Elastic's default APM distribution were also excluded here because their default licenses (Functional Source License and Elastic License, respectively) are not OSI-approved open source, even though both are technically self-hostable.
Top Picks
Based on features, user feedback, and value for money.
| Tool | Starting price | Rating | Best for |
|---|---|---|---|
| Prometheus | Free | 4.4(71) | Teams building a metrics and alerting foundation for Kubernetes clusters or VM fleets. |
| Grafana | From $19/mo | 4.5(243) | Anyone who needs one dashboard view across metrics, logs, and traces pulled from multip... |
| Uptime Kuma | Free | 4.6(400) | Small teams and solo operators who want UptimeRobot-style monitoring without sending da... |
| SigNoz | From $199/mo | n/a | Teams already instrumenting with OpenTelemetry who want one self-hosted backend instead... |
| Loki | Free | 4.0(49) | Teams already running Prometheus and Grafana who want logs in the same stack without an... |
| OpenTelemetry | Free | 1.0(169) | Anyone building a self-hosted stack who wants to instrument once and route data to Prom... |
| Nagios | Free plan | 4.6(192) | Ops teams that want config-file-driven host and service checks without any dependency o... |
| Vector | Free | 4.9(16) | Teams that need to collect, transform, and route telemetry from many sources into Prome... |
| Falco | Free | n/a | Platform and security teams that need runtime threat detection on Kubernetes, not just... |
| Healthchecks.io | From $5/mo | n/a | Teams that need to know when a backup script or scheduled task silently stops running,... |
Teams building a metrics and alerting foundation for Kubernetes clusters or VM fleets.
Prometheus is 100% free and open source (Apache 2.0).
Watch out
Storage costs grow linearly with metric cardinality and retention period
Anyone who needs one dashboard view across metrics, logs, and traces pulled from multiple self-hosted sources.
Grafana OSS is completely free for self-hosted visualization.
Watch out
Metrics overage at $6.50 per 1,000 active series adds up with high-cardinality data
Small teams and solo operators who want UptimeRobot-style monitoring without sending data to a third party.
Uptime Kuma's pricing is exceptionally generous, being entirely free.
Watch out
Requires user's own server infrastructure
Teams already instrumenting with OpenTelemetry who want one self-hosted backend instead of three separate tools.
SigNoz offers a very generous pricing model with its free Community tier, providing full features and unlimited data for self-hosted users.
Watch out
Self-hosting requires engineering time
Teams already running Prometheus and Grafana who want logs in the same stack without an Elasticsearch-sized bill.
Loki's pricing is exceptionally fair and generous, as it is entirely free and open-source.
Watch out
Self-hosting infrastructure costs
Anyone building a self-hosted stack who wants to instrument once and route data to Prometheus, Loki, or SigNoz without lock-in.
OpenTelemetry offers an incredibly generous pricing model, as it is entirely free and open-source.
Watch out
Requires significant engineering effort
Ops teams that want config-file-driven host and service checks without any dependency on cloud infrastructure.
Nagios' pricing model, with a robust free tier and one-time purchase options for commercial versions, is quite generous compared to many subscription-based monitoring tools.
Watch out
Support beyond initial purchase is extra
Teams that need to collect, transform, and route telemetry from many sources into Prometheus, Loki, or Elasticsearch without a heavyweight agent.
Vector's pricing is exceptionally generous as it is entirely free and open-source.
Watch out
Requires internal engineering resources for deployment/maintenance
Platform and security teams that need runtime threat detection on Kubernetes, not just infrastructure uptime.
Falco's pricing is exceptionally generous as it is entirely free and open-source.
Watch out
Requires internal expertise for deployment/maintenance
Teams that need to know when a backup script or scheduled task silently stops running, not just when a server goes down.
Healthchecks.io offers a very generous free tier and a well-structured pricing model.
Watch out
Overage for log entries beyond tier limits
Other Monitoring worth considering
Beyond the editorial top picks, these are also strong choices we evaluated.
What Counts as an Open Source Monitoring Tool?
An open source monitoring tool ships its full source code under a license that lets you run, modify, and redistribute it without paying anyone, and you deploy it on servers or a Kubernetes cluster you control. That is a narrower bar than "self-hosted" alone. Plenty of vendors ship a self-hosted edition of a commercial product (source-available, not open source) that is free to run but legally restricted in ways MIT or Apache 2.0 code is not, or that gates the features you actually need behind a paid tier.
The tools on this list clear that bar in different ways. Some are permissively licensed end to end (Uptime Kuma under MIT, Prometheus and Falco under Apache 2.0). Others use copyleft licenses like AGPLv3 (Grafana, Loki) that require you to share modifications if you distribute the software, which matters for vendors reselling it but not for a company running it internally. A few, like SigNoz, follow an open-core model where the core product is fully open (MIT and Apache 2.0) and a separate enterprise module adds paid features like SSO, without touching what you get for free.
Why Self-Hosting Your Monitoring Stack Matters
The financial case is the most visible one. Datadog and New Relic price by host, by container, or by gigabyte of ingested data, and those numbers compound as infrastructure grows. Teams routinely see monitoring bills that rival their compute bill once they add APM, log management, and synthetic checks on top of base metrics. A self-hosted Prometheus and Grafana stack has no metering on data volume; the cost is the compute and disk you already control, plus the engineering time to run it.
The less visible case is control. Your metrics, logs, and traces often contain customer data, internal hostnames, and business logic you may not want sitting in a third-party SaaS platform under someone else's data retention policy. Self-hosting also removes an ironic failure mode: if your uptime monitor is itself a SaaS product, an outage at that vendor blinds you to your own outage at the same time. Running Uptime Kuma or Healthchecks.io on infrastructure independent from what they watch avoids that single point of failure. The tradeoff is real: you take on patching, scaling, and backup responsibility that a managed SaaS would otherwise carry.
Key Features to Look For
Check the actual LICENSE file, not the marketing page. MIT, Apache 2.0, BSD, GPL, AGPL, and MPL are OSI-approved. Business Source License, Functional Source License, and Elastic License are source-available, not open source, even when the software is technically self-hostable.
A self-hosted tool that silently calls a vendor's cloud for licensing checks or telemetry defeats the point. Every tool here runs with zero required external dependencies once deployed.
Check the GitHub commit history and release cadence before committing. An abandoned open source monitoring tool is a security liability, since you are the one responsible for patching it.
Prometheus-compatible metrics and OpenTelemetry-compatible traces and logs are the closest thing this space has to a standard. Tools that speak both formats slot into a stack you already run instead of forcing a rebuild.
SigNoz's ClickHouse backend needs real hardware at scale; Uptime Kuma runs comfortably on a $5 VPS. Match the tool's footprint to what you are willing to operate, not just what looks best in a demo.
When something breaks at 2am, a large community and searchable GitHub issues matter as much as the feature list. This is where newer open source projects trail Prometheus and Nagios.
Mistakes to Avoid
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Treating 'source-available' as 'open source.' Sentry's Functional Source License and Elastic's default license let you self-host, but neither is an OSI-approved open source license; check the actual LICENSE file, not the marketing page.
- ×
Deploying Prometheus alone and expecting months of metric history. The local TSDB is built for short retention; plan for Thanos, Mimir, or VictoriaMetrics before you hit the wall, not after.
- ×
Standing up Grafana and Loki without checking the AGPLv3 relicense against your company's open source policy. It rarely blocks internal use, but it is worth a five-minute legal check before rollout.
- ×
Underestimating the ops burden. A self-hosted stack replaces a SaaS subscription with patching, scaling, and backup work your team now owns.
- ×
Deploying an eBPF-dependent tool like Falco without checking kernel version compatibility first, which is a common cause of failed first installs.
Expert Tips
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Start with Prometheus, Grafana, and Alertmanager before adding anything else. That combination alone covers most infrastructure monitoring needs.
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Pair Loki with Grafana instead of standing up a full ELK stack if your log volume is under a few hundred gigabytes a day; the cost difference is significant.
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Instrument with OpenTelemetry from day one, even if you start with a simple backend. Swapping backends later does not require touching application code again.
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Budget for a long-term storage layer (Thanos, Mimir, or VictoriaMetrics) before you hit Prometheus's local retention ceiling, not as an emergency fix after you already have.
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Run Uptime Kuma or Healthchecks.io in a different failure domain than what they monitor. If your monitoring stack and your production stack share the same outage, you find out about neither.
The Bottom Line
For most self-hosted stacks, Prometheus plus Grafana covers metrics and dashboards, Loki adds logs in the same style, and SigNoz is the strongest single answer if you want traces, metrics, and logs under one roof. Of the 10,000+ tools Toolradar tracks, these are the ones you can run entirely on your own infrastructure with a genuinely open source license, not a source-available demo of a paid product.
Frequently Asked Questions
What is the best open source monitoring tool overall?
There is no single best tool because monitoring is not one job. For metrics and alerting, Prometheus paired with Grafana is the standard self-hosted combination. For a single tool that covers metrics, traces, and logs together, SigNoz is the strongest open source option in 2026. For simple uptime and status pages, Uptime Kuma is the fastest to deploy.
Is Grafana actually free to self-host?
Yes. Grafana's core is open source under AGPLv3, and the self-hosted OSS build includes dashboards, alerting, and support for over 100 data sources with no user or dashboard limits. What is not free is Grafana Enterprise, which adds reporting, SAML and LDAP team sync, and fine-grained access control as a separate paid product.
Can I actually replace Datadog or New Relic with open source tools?
For most infrastructure and application monitoring, yes: Prometheus and Grafana for metrics, Loki for logs, SigNoz or OpenTelemetry plus a tracing backend for traces. The tradeoff is operational, not functional. Datadog and New Relic bundle hosting, scaling, and support into the subscription price; a self-hosted stack shifts that work onto your own team.
What is the difference between Prometheus and Grafana?
Prometheus collects, stores, and alerts on time-series metrics; it has no built-in dashboarding of its own beyond a basic query browser. Grafana is the visualization layer, reading data from Prometheus (and many other sources) to build dashboards. The two are almost always deployed together, not as alternatives to each other.
Is Uptime Kuma good enough for production use?
For uptime checks and public status pages, yes. Uptime Kuma is MIT licensed, runs in a single Docker container, and supports HTTP, TCP, DNS, and Docker container monitoring with around 90 notification integrations. It is not a replacement for full observability: it has no long-term metrics storage or log aggregation, so most teams pair it with Prometheus and Grafana rather than using it alone.
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