Cron Explainer
Explain cron expressions in plain English and list the next run times. Supports 5-field Unix, 6-field with seconds, Quartz, @macros and L, W, # tokens.
🔒 Runs entirely in your browser — nothing is uploadedWhat Cron Explainer does
Cron Explainer translates a cron expression into plain English and lists exactly when it will fire next. It understands the classic five-field crontab used by Linux, Kubernetes CronJobs, GitHub Actions and most hosting dashboards, the six-field form with a leading seconds field used by Spring, node-cron and croner, and seven-field Quartz expressions with a year. Macros such as @hourly, @daily, @weekly, @monthly and @yearly are expanded and explained too.
Instead of mentally decoding stars, steps, ranges and lists, you see sentences such as "Every 15 minutes between 09:00 and 17:59, on Monday through Friday", a table that shows which values each field matches, and the next 5, 10 or 25 run times in your local time zone or UTC. Extended tokens are supported as well: L for the last day of the month, 15W for the weekday nearest the 15th, MON#2 for the second Monday and 5L for the last Friday. Names such as JAN and MON work in any field where they make sense.
Private browser-based workflow
All processing happens inside your browser with client-side JavaScript. The tool does not upload snippets, configuration values, generated data, query text, or copied examples to a server, and it does not require an account. That local-only model matters for developer utilities because the content pasted into them often looks like real application data. Keeping the work local reduces risk and keeps the interaction fast because there is no network round trip.
Practical tips
When both the day-of-month and day-of-week fields are restricted, standard cron runs the job when either matches — 0 0 1 * MON fires on the 1st and on every Monday. The explanation spells this out because it surprises many people. Quartz numbers weekdays 1–7 starting on Sunday, while Unix cron uses 0–7 with both 0 and 7 meaning Sunday; the tool detects Quartz from the ? token or a seventh field. A cron expression usually runs in the scheduler's time zone, not your browser's, so use the UTC view for servers and watch out for daylight-saving transitions. For production jobs, pair a human-readable explanation with monitoring and idempotent job behavior.
How to use
- Enter cronPaste an expression such as 0 9 * * MON-FRI, or click a preset.
- Read the explanationSee the schedule in plain English and a field-by-field breakdown.
- Check upcoming runsReview the next run times in local time or UTC.