Every developer has typed a cron expression, deployed it, and then quietly wondered whether the job runs at 3 AM daily or every minute of 3 AM daily. (Those are different expressions. One of them will page you.) Our free cron expression generator ends the guessing: build the schedule visually, read it back in plain English, copy the expression. The cron generator runs entirely in your browser — no signup, no server, no telemetry on your infrastructure schedules.
A standard cron expression is five fields separated by spaces, read left to right: minute (0–59), hour (0–23), day of month (1–31), month (1–12), day of week (0–6, where both 0 and 7 usually mean Sunday — the first of many charming inconsistencies). Each field takes a number, a * wildcard, a range like 1-5, a list like 1,15, or a step like */15. So 0 3 * * * is "3:00 AM every day," and * 3 * * * — one character different — is "every minute between 3:00 and 3:59." That single asterisk is the most-paged character in ops history.
The greatest hits: */15 * * * * runs every fifteen minutes. 0 * * * * is the top of every hour. 0 9 * * 1-5 is 9 AM on weekdays — the standup special. 0 0 1 * * fires at midnight on the first of the month, which is when invoice jobs and quota resets live. 0 2 * * 0 is 2 AM Sunday, the traditional home of backups and the maintenance window. Build any of these in the generator and it hands you the expression plus the English translation, so what you deploy is what you meant.
Day-of-month vs day-of-week is OR, not AND. The ancient trap: 0 0 13 * 5 does not mean "Friday the 13th." In standard cron, when both day fields are restricted, the job runs when either matches — so that expression fires every Friday and every 13th. Timezones: cron runs in the server's timezone, which is usually UTC and usually not where you live. "9 AM" in your head is 0 13 or 0 14 on the server depending on daylight saving — decide in UTC and convert deliberately (our timestamp converter helps when you're debugging what actually ran). DST double-fires and skips: jobs scheduled between 1 and 3 AM local time can run twice or never on changeover nights. Schedule critical jobs outside that window. Nonstandard extensions: six-field seconds variants (Quartz), @daily shortcuts, and L/W modifiers exist in some schedulers and not others — know which dialect your platform speaks before you copy an expression from a random forum answer.
The workflow that never pages: build the expression in the cron expression generator, read the plain-English translation back, and check the next few fire times match your intent. Then, in production, log every run with a timestamp at the top of the job — future-you debugging "did it run?" will send thanks. If your job wraps a script with a regex or parses dates, the free regex tester and timestamp converter live in the same no-signup toolbox.
Cron used to be for backups. Now it's the heartbeat of automation: scheduled agents, content pipelines, data pulls, report generation. We build QADIR OS — a sovereign agentic operating system where scheduled, recurring work is the whole point: an agent that runs your morning triage at 6, your content drop at 9, your backup at 2. The humble cron expression is the oldest ancestor of that world, and it still runs most of it. Worth getting right.
How do I run a cron job every 5 minutes? */5 * * * * — the step syntax in the minute field. Every 30 minutes is */30 * * * *; every 2 hours is 0 */2 * * * (note the leading 0, or it fires every minute of every second hour).
What do @daily and @reboot mean? They're shortcut aliases some cron implementations accept: @daily equals 0 0 * * *, @hourly equals 0 * * * *, and @reboot runs once at startup. Handy, but not portable — spell out the five fields if your expression might travel between systems.
Does cron support seconds? Standard Unix cron doesn't — one minute is the finest grain. Quartz (Java) and some cloud schedulers add a sixth seconds field, which is why expressions copied between platforms sometimes shift by one position and break silently.
Cron syntax is five fields, four symbols, and two or three traps — learnable in an afternoon, but never worth risking a production schedule on memory. Generate it, read the English back, deploy with confidence. Free, in your browser, no account.
Schedule it right the first time. Use the free cron expression generator, then join early access for QADIR OS — the sovereign agentic OS where your schedules run real work on your own hardware. No card required.