UptimeRobot is the best website monitoring service for uptime alerts and is used by developers, marketers, and business owners.

Oh Dear is an all-in-one website monitoring tool for uptime, broken links, SSL certificates, performance, and application health, used by developers and tech teams.

Honeybadger is an all-in-one error tracking, APM, and logging platform for developers to find and fix application issues faster across Ruby, PHP, Python, and more.

Healthchecks.io is a cron job monitoring service for developers and teams to ensure timely execution of background jobs.

Cronitor is a monitoring tool for cron jobs, websites, APIs and more.