updown.io is described as 'HTTP monitoring solution with a clean UI and a cheap and simple pricing. It notifies you of downtimes by email or SMS and provides a public status page you can share'. There are more than 100 alternatives to updown.io, not only websites but also apps for a variety of platforms, including SaaS, Windows, Linux and Android. The best alternative is Better Uptime, which is free. Other great sites and apps similar to updown.io are UptimeRobot (Freemium), Pingdom (Paid), Freshping (Free) and StatusCake (Freemium).
Dashboard with 50 Monitors, Checked Every 5 Minutes, Totally Free. Monitor HTTP(S), Ping, Port and check Keywords. Get alerted via e-mail, SMS, Twitter, web-hooks or push. View uptime, downtime and response times.
Pingdom web site monitoring and other infrastructure for you and instantly let you know when anything goes wrong. Measure uptime, downtime, and the performance of your website as experienced by visitors.
StatusCake.com is a free website monitoring tool which allows users to track up to 10 websites and get alerted when their site is down or is having trouble. Downtime root cause analysis is included in the free plan to help users diagnose and fix issues.
Pingbreak is an original and free monitoring service. Get notified through Twitter if your website is down. Pingbreak checks all of your websites each minute and alert you instantly by Direct Message (DM).
GitHub-powered open-source uptime monitor and status page. Monitor uptime every 5 minutes Using GitHub Actions, monitor unlimited webpages every 5 minutes, and store version-controlled response time stats.