Cron Expression Builder & Schedule Generator
Visually design crontab expressions without memorizing complex syntax. Convert cron strings into human-readable English, calculate future execution times, and generate production crontab commands.
"Every 15 minutes"
Crontab Symbol Reference
- * : Any value (wildcard)
- , : Value list separator (e.g.
1,3,5) - - : Range of values (e.g.
1-5) - / : Step values (e.g.
*/10)
What is a Cron Expression?
A Cron Expression is a string of five (or sometimes six) fields separated by white space that represents a recurring schedule in Unix and Linux operating systems. The standard POSIX cron format controls the crontab background daemon to automate maintenance tasks such as database backups, index rebuilding, email queues, and cache flushing at specific minute, hour, day of month, month, and day of week intervals.
The NexTools Cron Expression Builder allows sysadmins, DevOps engineers, and full-stack developers to construct, inspect, and translate cron syntax visually. It translates arcane tokens into clear English sentences and calculates real-time future execution dates instantly within the browser.
Key Capabilities & Features
Bi-Directional Visual Sync
Configure schedules using intuitive radio buttons and checkboxes or type raw expressions directly into the text field.
Plain English Interpretation
Converts cryptic notation (e.g. 0 3 * * 1-5) into clear sentences ("At 03:00 AM, Monday through Friday").
Upcoming Execution Schedule
Simulates the cron engine and projects the exact dates and times of the next 5 trigger runs with countdown timers.
Production Crontab Commands
Combine your schedule with custom CLI commands, paths, and redirect outputs for 1-click clipboard copying directly into crontab -e.
How to Use the Cron Builder
Pick an Interval or Preset:
Select one of the quick preset pills (such as "Every 15 min" or "Daily midnight") or use the visual field tabs to configure custom minutes and hours.
Verify Plain English & Future Triggers:
Read the green human-readable translation banner and verify the "Next 5 Trigger Dates" list to ensure the schedule matches your intended operational window.
Copy to Server Crontab:
Click "Copy" for the standalone 5-field expression or enter your shell command to copy the entire line for your Linux server or Docker entrypoint.
Frequently Asked Questions
What are the 5 standard fields of a crontab entry?
The 5 fields in standard Unix crontab are: 1. Minute (0-59), 2. Hour (0-23), 3. Day of the Month (1-31), 4. Month of the Year (1-12), and 5. Day of the Week (0-6, where 0 is Sunday).
What is the difference between * and */5?
An asterisk (*) means "every single unit" (e.g. every minute). A forward slash with a number (e.g. */5) specifies a step value, meaning "every 5th minute" (0, 5, 10, 15, ...).
Does Sunday equal 0 or 7 in cron?
In standard POSIX crontab, Sunday is represented by 0. Many modern implementations (including Vixie cron) accept both 0 and 7 as Sunday.