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Validate standard five-field cron expressions with lists, ranges and steps, explain the fields, and calculate the next ten UTC occurrences without executing a command.
minute · hour · day of month · month · day of week
Simple workflow
How to use Cron Expression Parser
- 1Enter exactly five cron fields.
- 2Choose the UTC instant after which matching runs should be found.
- 3Parse the expression and review its explanation and next ten UTC occurrences.
Good to know
Frequently asked questions
Which cron format is supported?
Standard five-field minute, hour, day-of-month, month and day-of-week syntax. Quartz and AWS six- or seven-field forms are not supported.
Which timezone is used?
This version evaluates schedules explicitly in UTC and shows that assumption beside the input and results.
What happens when day of month and weekday are both restricted?
Either field can match, following common Vixie cron OR semantics. Other scheduler implementations can differ.
Does the parser execute anything?
No. It validates and calculates a schedule only; it has no command or process execution path.
Practical guide
Explain five-field cron schedules and list upcoming UTC runs
A standard five-field expression contains minute, hour, day of month, month and day of week. This parser supports asterisks, integers, comma lists, ranges and steps, then calculates the next ten matching times in UTC.
When day of month and day of week are both restricted, this implementation uses common Vixie cron OR semantics: either field can make the date match. Other cron systems can differ, so check the scheduler that will actually run the job.
Worked example
Parse a weekday work-hours schedule
- Start with
- */15 9-17 * * 1-5
- Choose
- Choose a UTC start instant.
- You get
- Every 15 minutes from 09:00 through 17:59, Monday through Friday, in UTC.
Tips for a useful result
- Use exactly five fields; Quartz and AWS variants are outside this version.
- The next-run search is bounded to ten years.
- The parser describes a schedule only and never executes commands.
Supported syntax, timezone and privacy
Names such as MON or JAN and special tokens L, W, #, ?, aliases and @reboot are not supported. Day of week uses 0 or 7 for Sunday through 6 for Saturday.
Evaluation is deliberately UTC so browser locale is never an invisible schedule setting. Cron expressions and results stay local and are not persisted.
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