Website monitoring for the sites you look after
90 days · two outages · one spell of refused checks
The certificate lapses on a Sunday. The domain quietly expires. A staging robots.txt ships to production and search traffic drains away over a fortnight. Owl Keeper watches uptime, certificates, domain registration, DNS and mail authentication on one page — and tells you before your client does.
Start monitoring — it's freeTen sites free. No card, no trial timer.
https://example.com
24h
100%
https://api.example.com/health
24h
98.2%
smtp.example.com:587
24h
99.9%
Websites, mail servers and TCP ports — alongside certificates, domains, DNS and mail records, on one page.
An uptime check asks one question and gets one answer. None of the following would fail it, and every one of them takes a site off the internet or quietly stops it earning — which is why they are watched here rather than sold to you as four more subscriptions.
GET https://example.com
200 OK · 188ms
What it never asked
Expiry dates, the issuing authority, whether the chain is complete and whether the certificate actually covers the hostname. Domain registration is read from the registry, along with the registrar lock and DNSSEC — so a transfer someone did not authorise shows up as a change, not as a surprise.
SPF, DKIM, DMARC and MTA-STS decide whether your mail reaches an inbox or a spam folder. SPF lookups are counted through every include, because passing eleven is a silent failure that leaves the record looking perfectly reasonable.
A stray noindex or a copied "Disallow: /" takes a client's traffic to zero over a few days, and it is invisible until somebody notices the phone has stopped ringing.
HSTS, Content-Security-Policy, cookie flags and whether plain HTTP still answers without redirecting. Reported as findings you can read, not a letter grade you have to defend.
Which of the conventions an AI agent looks for you actually publish — llms.txt, an MCP server card, Content Signals, an API catalogue. Recorded as facts, never as faults: publishing none of them is an ordinary site, not a broken one.
Only changes are written down. A check that finds the same thing as yesterday records nothing, so the history is the list of things that actually moved — the issuer, the nameservers, the DMARC policy — instead of a year of identical rows.
Enough to answer "is it up, and how has it been lately?" without a dashboard you need training for.
Check a URL for the status code you expect and a keyword in the body, open a TCP port to see if it answers, or greet a mail server and require STARTTLS. One tool for the three things that usually break.
Every check is kept as a heartbeat, so you get uptime over 24 hours, 7 days and 30 days, a 90-day history bar, and a response-time chart with downtime shaded behind it.
Every monitor hangs off a site, so a hostname carries its certificate, its domain registration and its mail records alongside its uptime. Tag the sites you look after and filter the whole estate down to one client.
Pause a monitor during planned maintenance and the scheduler skips it — no noise, no false incidents. You can still run a check by hand while it is paused, and nothing you have already recorded is thrown away.
An alert is an interruption, and most monitoring earns yours cheaply. Nothing here is called down until it has failed the number of times you set, from more than one place — so the message that does arrive is one worth stopping for.
https://api.example.com/health
Down after 3 checks in a row. Frankfurt and Singapore could not reach it either, so this is the site rather than the route to it.
Nothing is called down until it has failed the number of times you set. A firewall answering 403 is reported as refusing the checker rather than as an outage, because the two are not the same thing and only one of them is your problem.
Paste a Slack or Discord URL and messages are formatted for it. Anything else receives signed JSON, so you can put changes wherever your team already looks.
Uptime, which services are answering, and when the certificate and registration renew — on an unguessable link that never shows monitor names, addresses or anything from the security checks. Withdraw it and the link stops working.
The whole interface, including the alerts you are emailed. Set it per account, so one person can read it in Spanish while a colleague reads the same site in English.
No card, no trial timer, and every check on every plan. Create an account, add your first site, and see what it finds.