Cron doesn't complain when it breaks. A backup script that died three weeks ago, a report that never generated, a nightly sync that silently started failing — cron's failure mode is silence, and silence is the worst kind of bug. Cron job monitors solve this with a dead man's switch: your job sends a heartbeat ping when it finishes, and the monitor alerts you when the ping never arrives. These eight tools all offer a genuinely usable free tier.
How cron job monitors work
The pattern is the same everywhere. You create a check in the dashboard, which gives you a unique ping URL. At the end of your scheduled job you fire off one HTTP request to that URL. The monitor knows your expected schedule, so if the ping arrives late, never arrives, or arrives with a non-zero exit code, it pages you through email, Slack, webhooks, or another channel. Most services also support start/fail signals so they can measure job duration and flag overruns. A minimal wrapper looks like this:
#!/bin/bash
PING="https://hc-ping.com/your-uuid-here"
/usr/bin/curl -fsS -m 10 --retry 5 "$PING/start" >/dev/null
if /usr/local/bin/nightly-backup.sh; then
/usr/bin/curl -fsS -m 10 --retry 5 "$PING" >/dev/null
else
/usr/bin/curl -fsS -m 10 --retry 5 "$PING/fail" >/dev/null
exit 1
fiNo agent, no daemon, no library required — though most tools do offer official SDKs and Kubernetes or GitHub Actions integrations if you want deeper wiring.
1. Healthchecks.io — the open-source all-rounder
Healthchecks.io is the reference implementation of heartbeat monitoring: simple, battle-tested, and generous. The free hosted tier gives you 20 checks with up to 100 pings per day and no time limit, which covers a serious cron fleet for small teams and side projects. Set grace periods so long-running jobs don't trigger false alarms, tag checks by project, and attach log output to pings. Alerts flow through email, Slack, webhooks, Telegram, and PagerDuty. The killer feature for independence-minded teams is that the whole thing is open source under a BSD licence — you can self-host unlimited checks on your own infrastructure if you ever outgrow the free tier. Pair one curl line per job and you're monitored in minutes.
2. Cronitor — schedule-aware monitoring
Cronitor stands out because it actually understands cron expressions. Instead of only checking that a ping arrived on time, it reads your schedule and tracks whether each job started when it should, how long it ran, and whether that duration is drifting. That's how it catches slow rot — the backup that used to take 40 minutes and now takes 4 hours — not just hard failures. The free tier gives you 5 monitors with 7-day history and three alert integrations, which is enough for the critical handful of jobs that would page you at 2 AM. It also ships built-in log capture, a clean API, and native integrations for Kubernetes CronJobs, GitHub Actions, Vercel Cron, and Render. If your jobs matter enough to have analytics, Cronitor's free tier is the place to start.
3. Dead Man's Snitch — the minimalist original
Dead Man's Snitch pioneered the dead man's switch model and it hasn't moved an inch since: your job pings a unique URL, and if the ping doesn't arrive on schedule, you get an alert. That's the entire product, and that's the point. The free tier covers 1 snitch, which sounds thin until you realise most people use it for exactly one thing: the backup, the sync, or the billing run that absolutely must happen. Alerts go to email, webhooks, PagerDuty, and Slack. There are no dashboards to get lost in and nothing to tune. If you want the smallest possible surface area between you and "did the backup run," this is it.
4. Better Stack — heartbeats inside a bigger observability suite
Better Stack is primarily an uptime and incident-management platform, but its heartbeat checks make it a strong cron monitor too. The advantage is consolidation: cron alerts, uptime checks, log management, and on-call escalation all live in one incident timeline with a genuinely beautiful UI. The free tier includes heartbeat monitoring alongside its other free-tier allowances, so a team already using Better Stack for uptime gets cron monitoring without another vendor. Alerts cover email, SMS, phone calls, Slack, and webhooks — a deeper escalation path than most single-purpose monitors. Pick this one if your cron jobs are one incident source among several and you want everything in a single on-call flow.
5. UptimeRobot — heartbeat plus 50 free monitors
UptimeRobot is famous for its 50-monitor free tier, and those monitors include heartbeat-style checks alongside classic uptime probes. That makes it an easy first monitor for developers who want both "is the site up" and "did the job run" in one dashboard. Setup is the same curl-to-URL pattern, and alerts land via email, Slack, and webhooks. It won't give you duration analytics like Cronitor or log capture like Better Stack, but if your goal is covering a lot of jobs for zero pounds, the free quota is unmatched among hosted options.
6. Uptime Kuma — self-hosted everything
Uptime Kuma is the free-and-self-hosted answer. Run it on a cheap VPS or a spare Raspberry Pi with Docker and you get unlimited monitors — including push monitors that work exactly like heartbeat checks for cron jobs — with a gorgeous real-time dashboard and notifications via email, Telegram, Discord, Slack, webhooks, and dozens more. There is no free-tier clock ticking and no vendor lock-in. The trade-off is the obvious one: you now operate the monitoring itself, so put your Uptime Kuma instance on different infrastructure from the jobs it watches, or the host that dies takes the watchdog with it.
7. Sentry Crons — cron monitoring inside your error tracker
If your team already lives in Sentry, Sentry Crons is nearly a no-brainer. It monitors scheduled jobs directly inside the issue tracker: a missed or failing cron appears as an alert next to the errors and performance traces from the same deployment. That context is genuinely useful — when the nightly import fails, you see the cron alert and the exception from the same run in one view. It works for cron jobs, Kubernetes CronJobs, and scheduled tasks across languages with the same SDK you're probably already shipping. Check Sentry's current free tier for the exact monitor allowance; it folds cron monitoring into an error-tracking budget you may already be paying for or getting free.
8. Honeybadger check-ins — exit codes and output capture
Honeybadger built its name on error tracking and added check-ins for cron jobs with a useful twist: your pings can carry exit codes and captured output. That means the alert tells you not just that the job failed, but how it failed — the stack trace or stderr is right there in the notification. It's a small thing that saves a surprising amount of midnight debugging. Check-ins sit alongside Honeybadger's error, uptime, and status-page features, so it suits teams that want one error-first platform. The free tier covers a modest number of check-ins, enough to wrap your most important scheduled jobs with real diagnostic context.
Choosing the right one
Match the tool to the job, not to a ranking. Healthchecks.io or UptimeRobot for maximum free coverage; Cronitor when schedule awareness and duration trends matter; Dead Man's Snitch for a single critical job; Better Stack, Sentry, or Honeybadger when cron monitoring should live inside an existing observability stack; Uptime Kuma when you want unlimited monitors and full control on your own hardware. Whatever you pick, the integration pattern is identical — one curl per job — so switching later costs almost nothing. The only real mistake is leaving cron unmonitored.