Deepak Shukla
    By
    Founder & CEO, Pearl Lemon · Updated
    Reviewed 162 days ago
    First published 2026-05-05

    Best Open-Source Website Monitoring Tools (2026): 7 Tested

    Editorial guide to Best Open-Source Website Monitoring Tools (2026): 7 Tested. Verify current vendor documentation, product limits, and pricing before making a decision.

    TL;DR

    Use this shortlist to decide which products are worth evaluating. Current vendor documentation and a proof of concept are the reliable sources for feature, pricing, and operational-fit decisions.

    What "open source" means here — and the licences we excluded

    At-a-glance comparison

    #ToolFree planPriceEditorial fit
    1
    Uptime Kuma
    MIT-licensed, one-command Docker install, sane dashboard
    		Self-host MIT — free forever$0 — self-host MIT licensed35/40
    2
    SigNoz
    Open-source Datadog alternative — MIT, OTel-native
    		Self-host MIT — free forever$0 self-host; SigNoz Cloud from $49/mo if you change your mind34/40
    3
    Gatus
    YAML-config-as-code uptime monitoring, Apache 2.0
    		Self-host Apache 2.0 — free forever$0 — self-host Apache 2.034/40
    4
    Healthchecks.io
    BSD-2-licensed cron + heartbeat monitoring, also self-hostable
    		Hosted: 20 checks free; self-host: unlimitedHosted free; self-host $0; Hobbyist tier $5/mo34/40
    5
    OneUptime
    Apache 2.0 all-in-one — uptime, status pages, incident management
    		Self-host Apache 2.0; cloud free for 1 user$0 self-host; Growth from $22/mo cloud31/40
    6
    Nagios Core
    GPLv2 — the original open-source monitoring tool
    		Nagios Core GPLv2Core $0; Nagios XI from $1,995 one-time27/40
    7
    Zabbix
    AGPL — full-fat infra + web monitoring
    		Self-host AGPL$0 self-host; paid support tiers from Zabbix LLC29/40

    Scores out of 40 (Coverage + Alert quality + Cost + Ease, 10 each). "Open source" means: an OSI-approved licence — MIT, Apache 2.0, BSD, GPL, AGPL. Source-available licences (BSL, SSPL, ELv2) are excluded.

    How the options differ

    1

    Uptime Kuma

    MIT-licensed, one-command Docker install, sane dashboard

    Editorial shortlist entry — verify current vendor information
    Best for
    Operators who want a self-hosted UptimeRobot equivalent in one container.
    Skip if
    You need Core Web Vitals or distributed tracing.
    • MIT licence
    • Docker-compose install in under 5 minutes
    • Beautiful dashboard
    • Status pages built in
    • Single-node by default — needs work to HA
    • No CWV or RUM

    Verdict: Uptime Kuma is what we install for ourselves on side projects. The MIT licence is genuine, releases are monthly, the maintainer is responsive on GitHub. If your problem is "watch a handful of endpoints from infra I already own", this is the answer.

    $0 — self-host MIT licensed · source checked 2026-05-03; verify current pricingVisit Uptime Kuma
    2

    SigNoz

    Open-source Datadog alternative — MIT, OTel-native

    Editorial shortlist entry — verify current vendor information
    Best for
    Teams that want full observability (logs, metrics, traces) plus uptime, on their own infra.
    Skip if
    You only need to ping URLs — Kuma is simpler.
    • MIT licence (rare at this scope)
    • OpenTelemetry-native — no proprietary agent
    • Cloud version exists as exit
    • Self-hosting is a real operations project
    • Web monitoring is not the headline feature

    Verdict: SigNoz is the licence-clean answer to "we want to dump Datadog". Web monitoring is one widget inside a much broader observability tool — useful if you're already running services, overkill if you only have a marketing site.

    3

    Gatus

    YAML-config-as-code uptime monitoring, Apache 2.0

    Editorial shortlist entry — verify current vendor information
    Best for
    Teams that already keep all infra config in Git and want monitoring to live there too.
    Skip if
    You want a click-around UI to add monitors.
    • Apache 2.0 licence
    • Pure YAML config — diffable in Git
    • Lightweight Go binary, runs anywhere
    • No GUI for adding monitors
    • Smaller community than Kuma

    Verdict: Gatus is the GitOps answer. Every endpoint, threshold and alert routing lives in a YAML file you commit alongside your Terraform. Pull-request your monitoring changes, get them reviewed, ship them. That's the value proposition; if it doesn't appeal, use Kuma.

    $0 — self-host Apache 2.0 · source checked 2026-05-03; verify current pricingVisit Gatus
    4

    Healthchecks.io

    BSD-2-licensed cron + heartbeat monitoring, also self-hostable

    Editorial shortlist entry — verify current vendor information
    Best for
    Anyone who needs to know when a scheduled job silently stops running.
    Skip if
    You need website uptime probing rather than heartbeat monitoring.
    • BSD-2 licence
    • Hosted free tier (20 checks) and self-host both
    • Best-in-class cron monitoring
    • Heartbeat-only model — doesn't probe URLs itself

    Verdict: Healthchecks.io solves a different problem from the rest of this list — passive monitoring of "did the cron run". We include it because the licence is genuine open source and the self-host story is excellent (single Django app, runs in any Python environment).

    Hosted free; self-host $0; Hobbyist tier $5/mo · source checked 2026-05-03; verify current pricingVisit Healthchecks.io
    5

    OneUptime

    Apache 2.0 all-in-one — uptime, status pages, incident management

    Editorial shortlist entry — verify current vendor information
    Best for
    Teams that want a self-hostable PagerDuty + StatusPage + UptimeRobot in one stack.
    Skip if
    You're not ready to operate a multi-service Docker compose.
    • Apache 2.0 — clean licence
    • Bundles status page, incident, on-call, uptime
    • Heavy stack — many services
    • UI density is high

    Verdict: OneUptime is the ambitious entry — it's trying to be the open-source answer to four separate paid products at once. That breadth is also the cost: more services to run, more failure modes. If you want one OSS thing to replace four SaaS contracts, this is it.

    $0 self-host; Growth from $22/mo cloud · source checked 2026-05-03; verify current pricingVisit OneUptime
    6

    Nagios Core

    GPLv2 — the original open-source monitoring tool

    Editorial shortlist entry — verify current vendor information
    Best for
    Sysadmins who already know Nagios and have a plugin library.
    Skip if
    You're starting from scratch — the UX is from 2003.
    • GPLv2
    • Massive plugin ecosystem
    • Battle-tested for 25 years
    • Configuration is text-file gymnastics
    • UI is dated

    Verdict: Nagios is on this list because the licence is real and the plugin library is vast. We don't recommend it to greenfield teams — Kuma covers most of the same ground in 1% of the setup time — but if you have a Nagios installation already, you have no reason to leave.

    7

    Zabbix

    AGPL — full-fat infra + web monitoring

    Editorial shortlist entry — verify current vendor information
    Best for
    Telco / enterprise teams that want one tool for servers, network and web.
    Skip if
    Your only need is website uptime — this is overkill.
    • AGPL — copyleft but OSI-approved
    • Server, network and web checks unified
    • Strong enterprise adoption
    • Heavyweight install
    • AGPL has procurement implications for some

    Verdict: Zabbix is the right answer if your monitoring scope is bigger than a website — switches, servers, SNMP devices, plus the website. For a website-only scope, the operational weight isn't justified.

    $0 self-host; paid support tiers from Zabbix LLC · source checked 2026-05-03; verify current pricingVisit Zabbix

    How to evaluate the options

    Compare the provider's documented monitoring scope, check interval, notification workflow, retention, integrations, support model, security requirements, and commercial terms against the needs of your sites and team. Use a trial or proof of concept for claims that would affect your implementation.

    Sources cited

    Related rankings

    Ready to stop reading and start monitoring?

    Add your first site in under a minute. If Lemwatch is not the right fit, every alternative on this page is linked above — we would rather you pick well.

    • 10 sites monitored free, forever — no credit card
    • Uptime, speed, SEO, SSL, malware and visual change checks on one bill
    • Email, Slack, Google Chat and webhook alerts with recovery notices
    • White-label PDF reports if you monitor sites for clients
    Start free — 10 sitesSee full pricing
    Changelog (1)
    • 2026-05-05 — First publication. 7 OSI-licensed tools tested.
    Start free — 10 sites

    Related help articles