[ooorrr]

One other suggestion -

One problem with these sorts of services is that when they're working, nothing happens, so if I don't get mails for a week, I don't know if that's because everything's been working or if you've stopped running the service.

There are lots of complex answers, but an easy one is just to have a "last checked" for each URL - it's ok if I have to go on-demand to make sure things are running. (A weekly/monthly update is nice too, just more work.)

[robotrout]

Expanding on that idea a little. Store the proof of operation on the clients own server.

Let them enter a url to a script on their own server, that you will POST to, whenever you check their server. The user can log POST's to a text file, DB, etc., so they know that you are actually monitoring them.

When they see that you haven't POSTed to that file for a while, they know you're out of business, and they are unprotected.

On second thought, make it easy on yourself, and use GET. It's not like there's anything confidential about it.

[uggedal]

I've been thinking of implementing webhooks as an additional form of notification, but not as a a presence mechanism. I like the idea, but given the simple nature of the service I'd have to give it some thought before implementing something like this.

[uggedal]

I'll give the "last checked" idea some thought. I'd need to store some additional data as I'm currently storing only abnormal behavior.

Regarding the weekly/monthly update: this is something I'm averse to. Other services do this and it kind of bugs me each time I get these.

[ooorrr]

I'm with you. I think the simplest solution is best here. I do expect you'll run into scenarios where last-checked-time will be data you'll want anyway...

[thinkzig]

Another option might be a weekly uptime report. That way I still know you're in business and I get some useful information.

[uggedal]

Sounds like a premium feature to me ;-)