Apps similar to SiteAlert include Upzilla, which has a free version. Other options are Silent Down, Lean20 Ping, Status List and Hexadecimal. In total there are six Uptime Monitor Services like SiteAlert for the web.
Monitor your website, server, API, application, service and get notified if your resources have some problems with availability. Upzilla notifies you in Slack, Telegram, Messenger, or by email. Works also as a public status page with subscriptions.
Silent Down is a website uptime and performance monitoring platform, to keep an eye on your application and instantly alert you if any issues arrive.
Unlimited monitors checked from multiple location every minute. Monitor any port or setup a "heartbeat" that works well for cron jobs or any service behind a firewall. Be alerted as soon as your service is offline via email or app integration.
Standard uptime monitoring with alerts that include diagnostic information, timing breakdowns and dashboard snapshots. Configure alerts for HTTP statuses, reachability and performance thresholds.
