I used to use Cronitor but switched to the free (as in beer and speech) https://healthchecks.io
"The ops team consists of a single person, so multi-hour or even multi-day outages are possible".
>100 log entries per check
Do you know what that means? (On the pricing page)
* are my pings always right on time? What's the time variance?
* what IPs am I receiving pings from?
* who's pinging me -- a wget or curl utility, somebody using a browser, or some HTTP library?
The number "100" means that for each monitored job, the service will keep 100 most recent log entries, and will prune older entries.