Generate, explain, and validate cron expressions instantly in your browser. Visual builder and expression parser — free, private, and client-side.
Cron expressions are five (or six, depending on the system) space-separated fields that describe a schedule: minute, hour, day-of-month, month, and day-of-week. Each field accepts numeric values, ranges, lists, increments, and wildcards. Cron has been the de facto Unix scheduling format since the late 1970s and is now used far beyond Unix — by Kubernetes CronJobs, GitHub Actions, AWS EventBridge rules, Jenkins jobs, and almost every other scheduling system in production.
Reading and writing cron expressions by hand is error-prone. The fields are positional, the day-of-month and day-of-week interaction is non-obvious (a value in either field triggers the job, not both), and mistakes silently produce schedules that look right but fire at wrong times. A generator that translates plain-English schedules into correct cron syntax avoids these mistakes.
This tool offers two directions: building a cron expression from a friendly form (every Monday at 9 AM, every 5 minutes during business hours), and explaining an existing cron expression in human terms. Both run in your browser without any server interaction.
Cron syntax is dense and unforgiving. Common mistakes include confusing day-of-week numbering (Sunday is 0 or 7 depending on the system), forgetting that day-of-month and day-of-week use OR semantics, and misunderstanding the increment syntax (*/5 means every 5 starting at 0). A generator catches these by construction — produced expressions match what you described in the form.
Reading existing expressions is equally hard. A schedule like 0 9 * * 1-5 reads as every weekday at 9 AM once you know the syntax, but anyone unfamiliar with cron has to look up each field. Explaining the expression in human terms is faster than learning the syntax for one-off interactions.
Pick a schedule pattern, get the cron expression.
Standard cron has five fields: minute (0–59), hour (0–23), day of month (1–31), month (1–12), day of week (0–6 or 0–7, both Sunday). Each field accepts a single value, comma-separated list, range with hyphen, increment with /, or wildcard with *.
Day-of-month and day-of-week use OR semantics: if either is set to a non-wildcard value, the job runs when either matches. This is counterintuitive but matches POSIX cron behavior. Setting both fields produces a wider schedule, not a narrower one.
Extensions vary by implementation. Some accept a sixth field for seconds (Quartz, Spring); some accept ? as a wildcard alternative; some include @yearly, @monthly, @daily shortcuts. The generator produces standard 5-field cron suitable for most systems.