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Crontab Builder

Build cron schedule expressions visually — select time fields from dropdowns, choose a preset, and instantly see the cron expression, its meaning, and the next 5 scheduled run times.

import CopyButton from "./_CopyButton.astro"
Presets:
Cron Expression
* * * * *
Meaning
Every minute
Next 5 Runs
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    How to use Crontab Builder

    1. Choose values from the five dropdowns (Minute, Hour, Day of Month, Month, Day of Week) or click a preset button.
    2. Review the generated cron expression and its plain-English description.
    3. Check the next 5 scheduled run times, then copy the expression with the Copy button.

    What is Crontab Builder?

    A cron expression is a string of five fields (minute, hour, day-of-month, month, day-of-week) that defines when a scheduled task runs on Linux/Unix systems. Each field accepts specific values, wildcards (*), step intervals (*/5), ranges (1-5), or lists (1,3,5).

    This visual builder generates valid cron expressions from dropdown selections, provides a plain-English description of the schedule, and computes the next five fire times from the current moment. All computation happens client-side in your browser.

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    FAQ

    What is a cron expression?
    A cron expression is a string of five space-separated fields: minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-6, where 0=Sunday). It defines when a scheduled job runs on Unix-like systems.
    What does */5 in a cron field mean?
    The */5 notation means 'every 5 units'. In the minute field, */5 runs the job every 5 minutes (0, 5, 10, 15, ...). In the hour field, it runs every 5 hours.
    What does 0 0 * * * mean?
    This means 'at minute 0 of hour 0 every day' — the job runs at midnight (00:00) daily. It's the most common cron schedule for daily maintenance tasks.
    How are the next run times calculated?
    The cron expression is parsed and the next matching timestamps are found by iterating forward minute-by-minute from the current time, checking each timestamp against all five field constraints.

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