What The Cron is a lightweight plugin that seeks to answer the question “is my WordPress cron running?”.
What The Cron adds a WordPress admin Tools page that displays WP-Cron specific config values, schedules, and events. It also runs a ping every minute to check if the cron is running and will show a warning if there seems to be an issue as well as displaying which events are overdue.
This plugin is available for download for your site.