Cron Lab: Crontab Editor

Cron Lab reads and writes cron schedule expressions. Type one like "*/15 9-17 * * 1-5" and it tells you, in plain English, what it means, when it will run next in your timezone, and what might quietly break it. Cron Lab is free. Four features (Convert, In words, backup and restore, and the Home Screen widget) are part of Cron Lab Pro, a one-time $0.99 in-app purchase. Everything else listed below is free, and there is no subscription. FREE • Plain-English translation. Every expression becomes a clear sentence as you type, with a field-by-field breakdown below it. • Next runs. Accurate, DST-safe previews for any IANA timezone, in 12- or 24-hour time. • Visual builder. Tap together a valid expression: every N minutes, specific days, ranges, steps, and lists. • Schedule doctor. Explains why an expression never runs (February has no 30th), warns about leap-year-only dates, and flags the day-of-month / day-of-week OR rule that surprises almost everyone. • Examples and reference. A categorized library of common schedules and a built-in syntax cheat sheet. • Your library. Save and label expressions, and browse recent history. CRON LAB PRO (a one-time $0.99 in-app purchase) • Convert. Turn a standard crontab line into Quartz, Spring @Scheduled, AWS EventBridge, Jenkins, Kubernetes CronJob, or GitHub Actions. Handles the tricky parts (seconds, day-of-week numbering, the "?" rule) and includes copy-ready snippets, like the full CronJob YAML. • In words. Type "every weekday at 9am" or "the 1st of the month at noon" and get the matching expression. • Backup and restore. Save your whole library to a JSON file and load it back. • Home Screen widget. Pin a schedule to see its meaning and next run without opening the app. PRIVATE BY DESIGN • No ads, no tracking, no account. Your schedules never leave your device. • Works completely offline. • Clean, minimal design with full light and dark mode. • VoiceOver labels, legible contrast, large tap targets. • Supports 5-field crontab and 6-field (seconds) expressions, names (JAN-DEC, SUN-SAT), ranges, steps, lists, and @shortcuts (@daily, @reboot, and more). Cron Lab Pro is a one-time $0.99 in-app purchase, not a subscription.