Oh Dear provides comprehensive "website health" monitoring. It watches every monitored page for downtime, SSL certificate validity, DNS resolution, broken links, and scheduled task (cron) failures. The service is GDPR-compliant with EU data hosting. It offers instant notifications (email, Slack, SMS, etc.) and status pages for clients. According to the site, Oh Dear has performed over 67 billion checks and sent more than 38 million alerts. (No founder or start date is listed.)