CronPUT is a fairly self-explanatory name. Users sign up for an account and enter a list of webhook URLs, specifying a time or interval for each. At the specified time, a PUT request is sent to the URL. If anything other than a 200 comes back, an optional email is sent to the user.
I maintain a dozen or so Linux servers. Keeping track of that many cron webhooks is insane when they are all in different places and may or may not be working.