Documentation

HTTP checks

Unlike heartbeat checks, where your job pings us, an HTTP check polls a URL itself — the service sends a request at a fixed interval and alerts when the response stops looking right.

Parameters

Create the check in the dashboard (type "HTTP") or via the API — the http_config field:

Parameter	Default	Description
url	—	http/https, up to 2048 characters
method	GET	GET / HEAD / POST
timeout_sec	10	1–30 s for the whole request
expected_codes	2xx, 3xx	up to 10 values: classes ("2xx") and/or exact codes (301)
keyword	—	a string that must be present in the response body
keyword_absent	false	true — the string must be absent instead
follow_redirects	true	whether to follow redirects
headers	—	up to 10 custom headers
basic_auth	—	username + password
ssl_days_before	14	7 / 14 / 30 — how many days before certificate expiry to alert
confirmations	2	K consecutive failed probes before down (1–5)

An HTTP check's schedule is always a fixed interval (30–3600 s); cron expressions are for heartbeat checks only. Requests are sent with User-Agent: CronAlive-Probe/1.0. The keyword check does not apply to HEAD — the body is empty.

Minimum interval per plan

Free	Pro	Business
5 min	1 min	30 s

What counts as a failure

• a network error or exceeding timeout_sec;
• a response code outside expected_codes — the alert says "unexpected status 503";
• the keyword check: "expected keyword missing" or "forbidden keyword present".

Every probe is recorded: response code, latency (ms), probe region, error text. Latency is shown on the duration chart of the check page.

K confirmations and multi-region confirmation

One failed request is not an incident yet. The down status is assigned only after confirmations (2 by default) consecutive failed probes — an outage is detected within at most K intervals. The first successful response resets the counter and flips the check back to up.

In a multi-region setup a down additionally requires confirmation from a second region: after K local failures the probe job is dispatched to agents in other regions, and the flip happens only when at least two distinct regions see the failure within a 15-minute window. A local network issue of a single region does not cause a false alert.

SSL alerts

For https URLs the service watches the certificate expiry (checked every 12 hours, alongside a successful main probe). When ≤ ssl_days_before days remain, an alert goes to all enabled integrations of the project (webhooks receive the ssl_expiring event). Leave the "SSL" field empty to disable.

Behaviour

• a paused check is not probed at all;
• the probe queue refreshes every 30 seconds — the actual interval is honoured to that granularity;
• probing continues after a down: recovery is detected by the first successful response;
• down / up alerts work like for heartbeat checks: any channel, quiet hours, reminders.