AWS EventBridge cron vs rate expressions: which scheduler syntax to use

How this is calculated

EventBridge cron: cron(0 0 * * ? *) runs at midnight UTC every day. The 6 fields are minute, hour, day-of-month, month, day-of-week, year. The ? placeholder means 'no specific value' and is required in either the day-of-month or day-of-week field (one must be ?, the other a value). EventBridge rate: rate(5 minutes) is equivalent to every-5-minutes cron. Rate expressions only support minute, hour, and day units. For anything more complex than a fixed interval, use cron. EventBridge also supports timezone configuration per rule via the ScheduleExpressionTimezone parameter.

Verdict

Use rate() for simple recurring intervals (every 5 minutes, every hour, every day). Use cron() for wall-clock schedules (midnight UTC, first Monday of the month, 9 AM weekdays). Always specify a timezone on the rule to avoid the UTC surprise.