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Cron Job Helper

Build and validate cron expressions, preview the next runs in any time zone including DST, generate safe curl/wget web crons, plus CMS and Docker/DDEV recipes.

Build cron expressions without guessing

Cron is powerful, but its five asterisk fields are notoriously error-prone: a */5 in the wrong column, a swapped weekday, a forgotten zero — and the job runs too often, too rarely, or never. The Cron Job Helper takes the guesswork out. You set each field individually or type an expression directly, and the tool instantly shows you what the expression means, when it fires next and where it is wrong — every field is checked against the rules of Vixie cron and cronie, the cron that ships with the common Linux distributions.

The tool is for anyone working with scheduled tasks: developers who need a quick crontab line, admins decoding an inherited cron expression, and anyone wiring a CMS or framework scheduler (WordPress, TYPO3, Drupal, Laravel, Symfony) to a real system cron. It runs entirely in the browser — no account, no installation.

What the tool does — five sections

The interface is in English and split into five tabs:

  • Builder — the visual cron expression builder. For each of the five fields (minute, hour, day of month, month, day of week) you pick a mode: Every, Every N (*/N), Specific value, Range (A–B) or List / custom (a list or any other syntax you type yourself). Above sits the finished expression with a plain-text description and per-field errors and warnings; on the right, the next eight run times (Next Scheduled Runs) — calculated in your server's time zone, which you select, daylight saving changes included. Prefer typing? The Manual Input field also takes a complete crontab line including its command; Quick Presets offer 16 ready-made schedules with one click.
  • Web Cron — a generator for HTTP-triggered cron jobs: give it a URL and a schedule (or pull the schedule over from the Builder), and it builds the matching curl or wget line including timeout, HTTP method, log file, user-agent and HTTP basic auth. Every value is wrapped in single quotes, % is escaped for the crontab, and credentials can live in a ~/.netrc file instead of the command line.
  • CMS & Frameworks — ready-made crontab recipes for WordPress, TYPO3, Drupal, Laravel and Symfony, each with the recommended CLI path and — where the system has an HTTP trigger — a curl alternative.
  • Docker / DDEV — patterns for cron in containers: cron inside the container, a dedicated cron container, docker exec from the host, rootless Podman, and three DDEV variants.
  • Reference — a compact cheat sheet: field syntax, special characters along with the classic traps (the OR rule, steps across the hour, Quartz syntax), @ special strings, common examples, useful commands and the MAILTO mechanism.

Everything in the browser — nothing is sent

The Cron Job Helper is fully client-side. The builder, the plain-text parser, the next-run calculation and the web cron generator all run as JavaScript in your browser. There is no server call, no upload and no database: the URL you enter, an auth password or your schedule never leave your machine. The only thing the tool remembers is the time zone you picked for the preview, stored in your browser's localStorage. The tool also does not run any cron jobs — it only produces the expressions and command lines that you then add to your own crontab.

Try it now

→ Open the Cron Job Helper — set a field or click a preset, copy the expression, done. No account, free, right in the browser.

  • Docker tools — a companion to the Docker / DDEV tab when you prepare container setups.
  • Time & timestamp tools — check time zones and Unix timestamps before you lock in a schedule in the server's time zone.

Go deeper on the subpages: the Manual covers every tab in detail, Examples gives concrete expressions, and Tips & Tricks collects the classic pitfalls.