If your website, API, or side project goes down at 2 AM, you want to know about it before your users do. That's the entire point of uptime monitoring: a small service that pings your site every few minutes and alerts you the moment it stops responding.
The good news is you don't need to pay for this. Several solid free tiers exist. The bad news is "free" varies wildly — some check every 5-10 minutes, some cap you at a single monitor, some bury alerting behind a paywall entirely.
What actually matters when comparing them
Check interval is the biggest differentiator. A monitor checking every 10 minutes could let your site sit down for up to 10 minutes before anyone knows — often longer once the alert has to reach you too. A 1-2 minute interval is the difference between catching it early and hearing about it from a customer.
Number of monitors matters if you run more than one site or endpoint, which most people do. A free tier limited to one forces an upgrade almost immediately.
Where the alert lands matters more than people expect. Email is fine, but slow — it can sit unread for hours. An alert landing directly in Slack, Discord, or Telegram gets seen in seconds.
The landscape
UptimeRobot offers 5-minute checks for up to 50 monitors on its free tier — generous on count, less generous on speed.
Pingdom leans enterprise now and doesn't really have a meaningful free tier.
StatusCake offers similar tradeoffs to UptimeRobot: free plan, 5-minute checks, limited monitors.
Detection speed and alert placement matter more than raw uptime percentage — you can't fix what you don't know is broken.
Where PingKeeper fits
PingKeeper takes a different angle: 3 free monitors checked every 2 minutes, with alerts delivered straight to Telegram, Discord, or Slack. For a solo developer or small team running a couple of side projects, that combination covers the most common real-world need without asking for a credit card. You can see the full check-to-alert flow on the homepage.
How to decide
If you're monitoring one thing and a slower interval is fine, UptimeRobot's free tier is a reasonable default. If detection speed matters more than monitor count, a tighter interval with alerts landing where you already work will catch problems noticeably faster.
Either way — don't skip monitoring because it feels like a "later" problem. It takes five minutes to set up, and the alternative is finding out your site's been down for an hour from a tweet.
Stop finding out about outages from customers.
Free forever for up to 3 monitors — set one up in under a minute.
Start monitoring free