Cron Expression Parser

Parse and validate cron for Unix, GitHub Actions, Vercel, Cloudflare Workers, and AWS EventBridge — with timezone and DST support.

Standard 5-field cron: minute hour day-of-month month day-of-week
Type a cron expression above

    Examples

    Click any example to load it into the parser.

    How to Use This Cron Parser

    1. Select your platform — pick Unix, GitHub Actions, Vercel, Cloudflare Workers, or AWS EventBridge from the tabs above.
    2. Enter your cron expression — type or paste the expression, or click an example to auto-fill.
    3. Read the result — see the human-readable description and the next 10 scheduled runs in your selected timezone.
    4. Check DST warnings — runs affected by daylight saving transitions are flagged with a ⚠ icon.
    5. Pick a timezone — for Unix cron, choose any timezone. Serverless platforms (GitHub Actions, Vercel, Cloudflare) lock to UTC.
    6. Share your config — click "Copy link" to get a URL that encodes the expression, platform, and timezone for sharing in PRs and docs.

    Frequently Asked Questions

    Why doesn't my cron expression work in GitHub Actions?
    GitHub Actions only supports 5-field POSIX cron in UTC. If your expression uses the ?, L, W, or # operators, that's Quartz/AWS syntax and won't parse. Switch the platform selector to GitHub Actions to see GitHub-valid syntax.
    What's the difference between Unix cron and AWS EventBridge cron?
    AWS uses 6 fields (adds year) and supports ? (no specific value), L (last), W (nearest weekday), # (nth weekday of month). Unix cron is 5 fields and doesn't support any of these extended operators.
    How do I run a job in my local timezone with GitHub Actions?
    You can't directly — GitHub Actions runs cron in UTC. Convert your local time to UTC and use that. This tool does the conversion for you when you pick a timezone.
    What happens to cron jobs on DST transitions?
    Standard cron repeats or skips jobs at the spring-forward/fall-back hour. We flag this with a ⚠ next to affected runs in the next-10 list.
    Is * * * * * really every minute?
    Yes — every minute, every hour, every day, every month, every weekday. Be cautious on shared infrastructure.
    Can I share my cron expression with a teammate?
    Yes — every state is encoded in the URL hash. Click "Copy link" to share an exact configuration including the platform and timezone.
    Why doesn't crontab.guru support GitHub Actions, AWS, or Vercel?
    crontab.guru is built and operated by Cronitor (a paid cron-monitoring SaaS) and only supports their core Unix use case. We built this because every modern dev uses 3–5 different cron platforms across projects.
    How accurate are the "next run" times?
    Calculated from your selected timezone, using IANA tzdata for DST. The next 10 runs are computed deterministically from the expression and current time. Refresh the page to recompute from now.
    Does this tool work offline?
    Yes. After first load, the entire app is under 30KB and runs locally in your browser.
    What about Quartz or Spring cron expressions?
    Quartz uses 6 or 7 fields (similar to AWS but with seconds). We support a Quartz-compatible mode under the AWS platform selector for most cases. For seconds-precision, choose AWS or use a Quartz-specific tool.

    Related Tools

    More developer utilities from plato·tools — coming soon.

    About This Cron Expression Parser

    Cron expressions are the universal scheduling language for automated tasks across servers, CI/CD pipelines, and cloud platforms. But the syntax varies between platforms in ways that trip up even experienced engineers. A cron expression that works perfectly on a Linux server may silently fail in GitHub Actions because GitHub only supports UTC and rejects extended operators. AWS EventBridge uses six fields instead of five. Vercel and Cloudflare Workers impose minimum intervals that standard cron doesn't enforce.

    We built this cron expression parser because no existing tool addresses all five major platforms in one interface. The leading tool, crontab.guru, handles only Unix cron with no timezone selector, no DST awareness, and no platform-specific validation. That's fine if you only deploy to bare-metal servers — but modern applications span GitHub Actions for CI, Vercel for edge functions, Cloudflare Workers for global distribution, and AWS EventBridge for event-driven architectures. Each has its own cron dialect.

    This parser validates your expression against the rules of your chosen platform, shows a human-readable description, and computes the next 10 scheduled runs in your timezone — flagging any that cross a daylight saving transition. The share permalink encodes the full configuration in the URL hash so you can paste it into pull requests, Slack threads, or documentation. Your last configuration is saved locally in the browser, so returning visitors see their previous setup immediately.

    The tool runs entirely client-side. No data is sent to a server. The total page weight is under 30KB gzipped, designed to load instantly on mobile connections. Whether you're debugging why your GitHub Actions workflow fires at 3am instead of 9am, or figuring out how to express "first Monday of every month" in AWS EventBridge syntax, this parser gives you the answer in seconds.