In my newest side-project, Cronbox, users create a new monitor that is used to track whether a cron is running on time or not.

One of the requirements of this is that the cron schedule is configured to the server's timezone (typically UTC). To prevent confusion, I wanted to display the next run time in the users' local timezone.

Previously, I would have used Moment.js to convert the time on the client-side, i.e. in the browser. With Cronbox I came up with another solution using Laravel's Custom Casts feature.

When registering for the service, users select their local timezone which means I can convert the DateTime ahead of time (poor pun, sorry, not sorry!):

Since each monitor has a timezone also assigned to it, if there is no active user instance, it'll happily fall back to the monitor's local time.