SERPStream is a 100% free SEO tool. Members can keep track of their site's Search Engine Results Page position with updates as frequent as a dozen times a day. SERPStream have a great newsletter, sends email alerts, and have a state of the art keyword rank tracking dashboard.
WebGazer is an uptime monitoring platform that checks if your website is up as it should be and notifies you if anything goes wrong
Serpstat - Search analytics, Rank tracking, Backlink analysis and Site Audit tool.
UptimeRobot - Free Website Uptime Monitoring
SEO PowerSuite - Get all SEO tools in one pack - download free edition of SEO PowerSuite and get top 10 rankings for your site on Google and other search engines!
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.