Website and API uptime monitoring

Updated 25 October 2026 · By the Upcertain team

What an HTTP check does

Each check sends a request to your URL and compares the answer with what you expect. By default any status from 200 to 399 counts as up. You can name exact codes or ranges instead, such as 200, 2xx or 200-299, 301, so an API that should never redirect fails when it does.

• Methods, headers and body. GET, HEAD, POST, PUT, PATCH, DELETE or OPTIONS, up to 30 request headers and a body of up to 64 KB, so you can call a health endpoint the way your clients do.
• Basic authentication for pages behind a username and password.
• Timeout from 1 to 60 seconds (30 by default). A slow answer counts as a failure once it passes the timeout.
• Redirects are followed by default; turn that off to check the redirect itself.
• Certificate checks come with every HTTPS monitor: an expired certificate, a hostname mismatch or a broken chain fails the check, and you are warned 30, 14 and 7 days before expiry unless you pick other days.

Keyword checks for pages that fail politely

Some failures still return 200: a maintenance page, an empty product list, a framework error rendered as HTML. A keyword monitor passes only when a word or phrase is present on the page, or only when it is absent, with an option for case-sensitive matching.

How often to check

Intervals run from 30 seconds to 24 hours: 30 s, 60 s, 5 min, 30 min, 1 h, 12 h and 24 h. The Basic plan checks as often as every 60 seconds; Team and Business as often as every 30 seconds. Which interval to pick depends on how fast you need to know and how much noise you will tolerate.

Confirmed before anyone is alerted

A single failed request is often a dropped packet or a deploy restarting a container. When a check fails, Upcertain re-checks before opening an incident: from 0 to 5 confirmation checks, 15, 30, 60 or 120 seconds apart. New monitors start with one confirmation check after 15 seconds. The trade-off is explained in confirmation checks.

What happens when it is down

1. The incident opens with the cause: the status code, a timeout, a missing keyword, a DNS failure or a refused connection.
2. Each alert channel on the monitor is notified, after the delay you set for that channel (0 to 1440 minutes).
3. Reminders repeat while it stays down if you ask for them, every 5 to 1440 minutes.
4. Someone acknowledges the incident to stop the reminders.
5. When the check passes again the incident resolves and every channel gets the recovery, with the downtime.

Alerts go to email, Slack, Discord, Microsoft Teams, Google Chat or a signed webhook. The outage also shows on your status page if the monitor is on one.

Adding many sites at once

Guided setup turns one site into several monitors (the home page, a keyword check, the certificate) in one step. CSV import takes a file with header columns or one URL per line, shows a preview of every row and creates up to 200 monitors at a time. Monitors beyond your plan's limit are created paused rather than refused.

What it does not do

Checks run from one region, Seoul (AWS ap-northeast-2). Upcertain does not run browser or multi-step transaction checks, multi-region checks, DNS record monitors or phone and SMS alerts. If you need those, pick a tool that has them; if you need fast, confirmed HTTP checks with clear alerts and a status page, this is what Upcertain is built for.