Pingdom and Alertra. Alertra has had a perfect record for us for three years, meaning no false reports over that time (as far as we can tell). A bit more expe

Pingdom and Alertra. Alertra has had a perfect record for us for three years, meaning no false reports over that time (as far as we can tell). A bit more expensive, we use a single Alertra alert and multiple Pingdom alerts.