Is my data uploaded to a server when using the Cron Helper?

No. All processing happens 100% in your browser. Your data never leaves your computer, making this tool completely private and secure for sensitive information.

What cron expression formats are supported?

The Cron Helper supports standard 5-field cron expressions (minute, hour, day of month, month, day of week) as well as extended syntax with special characters like */, -, L, W, and #.

Can I preview when my cron job will run?

Yes. The tool provides a visual next-run preview showing upcoming execution times, making it easy to verify your schedule is correct before deploying.

Cron syntax uses five space-separated fields: minute (0-59), hour (0-23), day of month (1-31), month (1-12 or JAN-DEC), and day of week (0-7 or SUN-SAT, where 0 and 7 both represent Sunday). Each field accepts numbers, ranges, lists, steps, and wildcards.

What do the special characters in cron mean?

* (asterisk) matches all values. , (comma) separates list items. - (hyphen) defines ranges. / (slash) specifies step values. L (letter L) means 'last' for day of month/week. W (weekday) finds the nearest weekday. # specifies the nth occurrence of a weekday. ? means 'no specific value'.

How do I run a cron job every 5 minutes?

Use the expression */5 * * * *. The */5 in the minute field means 'every 5 minutes'. Similarly, */15 * * * * runs every 15 minutes, and */30 * * * * runs every 30 minutes.

How do I schedule a cron job at a specific time daily?

To run a job at 2:30 AM every day, use 30 2 * * *. The first field is the minute (30), the second is the hour (2), and the remaining fields are wildcards meaning every day, every month, every day of week.

How does cron handle timezones?

Cron evaluates expressions based on the system's local timezone. The cron helper generates expressions based on UTC or your browser's local timezone. When deploying to a server, ensure the server timezone matches your intended schedule.

How do I debug a cron expression that isn't running?

Use the cron helper to validate your expression syntax and preview the next 5-10 run times. Common issues include: incorrect timezone, wrong field order, forgetting that 0 = Sunday in day-of-week field, or using */1 instead of * (they're equivalent but * is preferred).

What is the difference between */1 and * in cron?

In the standard cron implementation, */1 and * are functionally equivalent — both mean 'every unit'. However, * is the conventional and cleaner way to express 'every minute/hour/day'. Some implementations may handle */1 differently than expected.

Can I schedule a cron job for specific weekdays only?

Yes. To run a job at 9 AM Monday through Friday, use 0 9 * * 1-5 (where 1=Monday, 5=Friday). To run only on weekends, use 0 9 * * 0,6 (0=Sunday, 6=Saturday).

How do I create a monthly cron expression?

To run a job at midnight on the first of every month, use 0 0 1 * *. To run on the 15th at 3:30 PM, use 30 15 15 * *. The day-of-month field controls monthly scheduling. Use L in this field for the last day of the month.

How do I read a cron schedule?

Each of the five standard fields represents: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-7, where 0 and 7 represent Sunday). The * wildcard means 'every'. For example, '0 9 * * 1-5' means 'at 9:00 AM, Monday through Friday'.

What is the difference between cron and crontab?

Cron is the system daemon that executes scheduled tasks on Unix-like operating systems. Crontab (cron table) is the configuration file that lists cron jobs and their schedules. Each user has their own crontab file, and the system crontab manages system-wide scheduled tasks.

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Cron Master

Generate, decode, and validate cron expressions with real-time previews

Cron Master

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Save

Valid schedule

* * * * *

“Every minute”

Cron fields

Minute0-59

Hour0-23

Day1-31

Month1-12

Weekday0-6

Minute0-59

*= every minute

*/5= every 5 minutes

0,30= at :00 and :30

15-45= minutes 15 through 45

Expression

paste or type

5/5valid

Deployment Snippet

Script path

(crontab -l ; echo "* * * * * /path/to/script.sh") | crontab -

This command appends the new schedule to your existing crontab without overwriting other jobs.

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Aug 7, 2026in 1 minute