UptimeRobot: A nice free website monitoring service

Over the weekend I’ve been looking around for a free service which monitors my websites. My requirement was that I want to be able to monitor both HTTP and HTTPS sites, I need support for authentication and the monitoring service should be able to check if a specific keyword exists within the watched site (instead of just assuming that a HTTP Status Code 200 is okay). Furthermore, I needed notifications in case of downtimes (Email and Pushbullet is fine for me).