Is It Down Right Now? - Network & Admin
SE Ranking - All-in-One cloud-based SEO software for agencies, marketing teams and webmasters
Site Down - Site down outage and downtime reports from SiteDown.co
DeskAlerts - Send alerts to any corporate device: PCs, phones, tablets, etc.
Is it Down? - Is it down can check if a website is down or is it just your PC that can not access it.
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.