As of May 2015, Browsermob is dead.
"Website monitoring for the masses. From basic free plans to enterprise level solutions, BrowserMob has it all - try our FREE website monitoring performance test.".
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Netweak Alternatives
Netweak is described as 'Delightful, minimalist monitoring platform that gives you insights on performance and availability for your linux servers & websites' and is a Uptime Monitor service in the network & admin category. There are more than 100 alternatives to Netweak for a variety of platforms, including Web-based, SaaS, Linux, Windows and Self-Hosted apps. The best Netweak alternative is Zabbix, which is both free and Open Source. Other great apps like Netweak are Uptime Kuma, Tianji, UptimeRobot and Nagios.