cutestat - Website Stats and Valuation. CuteStat.

OnlineOrNot - Uptime monitoring for software teams (even teams of one).

WebsiteOutlook - WebsiteOutlook is an all-in-one website that provides you detailed information on famous websites based on various data sources like traffic, page rank, and estimated ad revenue.

Statsignal - Statsignal is a simple and cost-effective way to monitor your website or server and publish a status page of your system.

Rankchart - Rankchart is one of the unique websites that allows you to examine your websites or watch competitors and locate rich information about website technologies, site reputation, errors, SEO, and ad-word recommendations.

Uptime Kuma - A fancy self-hosted monitoring tool.