What Is a Cron Expression Parser?
Cron syntax is compact and easy to write wrong: it is simple to swap the minute and hour fields, misjudge a day-of-week number, or misread */15 as "15 minutes past the hour" instead of "every 15 minutes." This cron parser online turns that dense string into a plain-English sentence and a list of actual upcoming run times showing the cron expression next run time, so you can confirm a schedule does what you meant before it goes into a crontab or a CI pipeline. Use it as a crontab guru alternative to explain cron expression syntax, as a cron job generator when you need the underlying five-field form of a preset, or as a cron syntax checker before deploying a scheduled job.
How the Five Cron Fields Work
Knowing how to read a cron expression starts with its five fields, separated by spaces, in a fixed order: minute (0 to 59), hour (0 to 23), day of month (1 to 31), month (1 to 12), and day of week (0 to 6). This is the standard five-field cron syntax used by the Unix cron job and most schedulers; it does not include a seconds field the way some non-standard schedulers, like Quartz, do. Reading left to right, an expression like 30 9 * * 1-5 means minute 30, hour 9, every day of month, every month, weekdays Monday through Friday, which is exactly the cron expression to plain english translation this tool produces automatically.
Cron Syntax Reference
An asterisk means every value in that field. A slash with a number, like */15, means every n-th value, so */15 in the minute field means every 15 minutes. An exact number means that specific value. A hyphen creates a range, so 1-5 in the day-of-week field means Monday through Friday. A comma creates a list of specific values, like 1,15 for the 1st and 15th of the month. Combining a range with a slash, like 0-30/10, adds a step within that range.
The Day-of-Week Ambiguity: 0 vs. 7
The POSIX cron standard, and implementations like Vixie cron, accept both 0 and 7 as meaning Sunday. This causes real confusion: cron day of week 0 or 7 is one of the most common points of disagreement between different cron implementations, and an expression copied from one system with a 7 for Sunday may not behave the same way when run through a different parser. This tool follows the 0 to 6 convention, where Sunday is 0 and Saturday is 6, matching JavaScript's native date handling; use 0 for Sunday here, not 7, to get the schedule you expect.
What This Tool Does Not Do
This tool parses the standard five-field cron syntax; it does not support the six-field Quartz format with seconds, and it does not treat 7 as an alias for Sunday the way some cron implementations additionally allow. Next-run calculation searches up to two years ahead to avoid unbounded computation for an expression that rarely or never matches. Nothing entered here is uploaded; parsing happens entirely in your browser.