Website checks
LastSeen fetches your site on a timer and tells you when it stops answering the way it should.
A website check fetches a URL on a timer, from LastSeen's side, and looks at the answer. Nothing needs installing on the site.
On Monitors, choose Add website monitor.
Settings #
| Setting | Meaning | Default |
|---|---|---|
| URL | What to fetch: https:// or http://. | none |
| Check every | From 1 minute to 24 hours. | 5m |
| Time out after | From 1 to 30 seconds. A slower answer is a failure. | 10s |
| Expected status codes | The status codes that mean all's well: a range or a list, like 200-299 or 200,204. | 200-399 |
| Keyword | Text that must be on the page, or (with absent) must not be, like an error message. Up to 200 characters. | none |
| Follow redirects | Follow them, checking each hop, and judge the final page. | on |
| Failures before down | Checks in a row that must fail before it's down (1 to 5). | 2 |
| Regions | Where to check from. | Oceania |
A check that's down comes back up on its first good answer, with a recovery alert.
What counts as a failure #
- the name doesn't resolve, or nothing answers;
- the connection or the TLS handshake fails, including an expired or invalid certificate;
- no answer within the timeout;
- a status code outside the expected ones;
- the keyword is missing (or present, with absent).
Each check's page shows recent results, the response time over the last day, and when the certificate expires.
Regions #
LastSeen can check from five regions: Oceania, North America, South America, Europe and Asia. Your plan decides how many a check may use (the Free plan: 1).
With more than one region, a check is down only when enough of them fail at once: Regions failing before down is most of them unless you set it, and never fewer than two. When some regions fail but not enough, the check is degraded: shown on the page, but not alerted on. One region's bad network path isn't your outage.
Private addresses #
Checks from LastSeen's regions only go to public addresses: a URL that points at a private network (like 192.168.1.10, or a name that resolves to one) is refused, at every redirect too. To check something on your own network, run an agent there and check from it; agent checks can also trust your own certificate authority, or accept any certificate.
Being a good neighbour #
All LastSeen customers' checks of any one site add up to at most 30 requests a minute; a check that would go over is refused when it's added, with the interval that would still fit. Our checker identifies itself as LastSeen-Monitor/1, and site owners can ask us not to check their site at all: see lastseen.io/bot.
If LastSeen's own network has trouble #
Alongside your checks, LastSeen checks a few very reliable sites of its own. If those fail too, the trouble is on our side, and your checks hold rather than alerting. See Staying quiet when you should.