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Developer & DevOps

⏰ Cron Expression Parser & Predictor

Decode and understand Linux crontab expressions instantly. Converts cryptic schedule patterns into human-readable descriptions and accurately forecasts the next 5 execution timestamps.

Minute
*/15
0-59
Hour
9-18
0-23
Day (Month)
*
1-31
Month
*
1-12
Day (Week)
1-5
0-6 (Sun-Sat)
Plain English Translation:
Every 15 minutes, between 09:00 and 18:59, Monday through Friday

Quick Preset Schedules

Upcoming Scheduled Runs (Local Time)

Understanding Unix Cron Syntax & Expressions

The Cron daemon is a time-based job scheduler foundational to Unix, Linux, and modern containerized server systems like Kubernetes (CronJobs) and cloud automation (AWS CloudWatch Events, GitHub Actions). Crontab configuration files specify commands to run periodically at fixed times, dates, or intervals.

However, compact crontab syntax can easily lead to costly scheduling blunders—such as triggering a heavy database dump every minute instead of once per hour. This interactive parser unpacks each field visually, validates wildcard constraints, and renders predictable chronological execution dates.

Cron Syntax Operators Guide

  • Asterisk (*): Wildcard matching all possible values in that field.
  • Comma (,): Value list separator allowing multiple specific integers (e.g. 1,15,30).
  • Hyphen (-): Specifies an inclusive numeric range (e.g. 9-17 for working hours).
  • Slash (/): Step intervals. */10 in the minute column executes every 10 minutes.

How to Use This Cron Parser

  1. Input Expression: Type your standard 5-part cron expression (e.g. 0 9 * * 1-5) into the input box or click any of the standard preset buttons.
  2. Review Human-Readable Translation: Read the instant natural language description explaining exactly when and how frequently the schedule runs.
  3. Inspect Next Execution Times: Check the projected list of the next 5 upcoming schedule trigger dates and times down to the second.
  4. Copy Expression: Click Copy 📋 to save the validated cron syntax into your server Crontab, GitHub Actions workflow, or cloud task scheduler.

Frequently Asked Questions (FAQ)

Q: Is Sunday represented as 0 or 7 in crontab?

In standard Linux/BSD crontab implementations, both 0 and 7 represent Sunday (0 = Sunday, 1 = Monday, ..., 6 = Saturday, 7 = Sunday). This parser safely treats both 0 and 7 as Sunday.

Q: Does this parser execute in my browser?

Yes. 100% of the lexical parsing and upcoming timestamp calculations run inside your browser. No schedule parameters or server configurations are transmitted to remote networks.

Q: How do Day-of-Month and Day-of-Week interact when both are set?

In standard Unix cron, if both the day-of-month and day-of-week fields are constrained (not wildcard *), the command runs when EITHER the day of the month OR the day of the week matches (OR logic).