For uptime monitoring, services like Pingdom, UptimeRobot, and StatusCake check your site regularly and alert you when it goes down. Most offer free tiers suitable for small sites.
For application performance monitoring, New Relic and Blackfire give deep insights into PHP performance, slow queries, and bottlenecks. They are invaluable for diagnosing performance issues on busy sites.
For log management, forward Drupal’s logs to a central service like Papertrail, Loggly, or a self hosted ELK stack. This makes it easier to spot patterns and errors across environments. Drupal’s own Recent log messages page is fine for small sites but becomes unwieldy at scale. Enable Cron monitoring too, since many background tasks depend on it running reliably. A good monitoring setup catches problems before users notice them.