Source on GitHub (MIT) — same preview engine as the CloudyBot dashboard.
Cron schedule helper — validate, translate, and preview your next run times
Paste a standard five-field cron expression, use quick presets, or open Build your schedule to pick days and times without memorizing field order — same patterns as the CloudyBot dashboard. This page shows a plain-English summary, next run times in the IANA timezone you pick, an optional quiet-hours check, and a compare mode for two expressions. Everything runs in your browser — your schedule is not uploaded. For token budgets on recurring AI jobs, pair this with the AI token counter and AI cost calculator.
1 · Expression 2 · Build 3 · Preview 4 · Options
Your cron expression
Order: minute · hour · day-of-month · month · day-of-week (Sun = 0 or 7). Ctrl+Enter copies the summary.
Quick presets (same as the CloudyBot dashboard):
Build your schedule
Pick a pattern — we generate the five-field cron string. Click Use this expression to copy it into the field above and refresh the preview.
Preview
The five fields are what crontab and CloudyBot use. Timezone and quiet hours below only change how we preview — they do not rewrite the string.
Type an expression above or choose a preset.
Next runs (in selected timezone)
Schedule figured out. Tell CloudyBot the same thing in plain English — it sets the recurring task up for you, or assigns it as a Specialist duty (a personalised AI agent with its own name and recurring jobs).
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Compare a second schedule
Optional: see when both expressions would next fire in the same minute (uses the timezone above).
Cron “dialects” — why paste fails on other platforms
This tool evaluates standard five-field cron. Other schedulers add fields or symbols.
| Platform | Notes |
|---|---|
| Linux crontab | Five fields; Sunday = 0 or 7 in many implementations. |
| GitHub Actions | Five fields in schedule.cron; UTC. Docs |
| AWS EventBridge | Six or seven fields; ? in day fields. Docs |
| Quartz | Six required fields + optional year; L, W, #. Docs |
How it works
A cron expression is a compact recipe for when something should run. The classic five-field form lists, from left to right: minute, hour, day of month, month, and day of week. Wildcards (*) mean “any,” steps like */15 mean “every N,” and ranges like 1-5 select a contiguous slice. If both day-of-month and day-of-week are constrained, common cron implementations treat the day as a match if either field matches — we follow that rule for preview so behaviour feels familiar to Linux users.
This page turns your expression into a human-readable sentence using the same labelling philosophy as CloudyBot’s dashboard, then walks forward minute by minute in your selected IANA timezone (for example America/New_York or Europe/Berlin). That means daylight saving shifts appear in the wall-clock times you expect for that region — handy when you are explaining an on-call rotation or a marketing send window to people who do not think in UTC.
Limitations are intentional: we reject symbols such as ?, L, W, and # for next-run preview because those belong to other schedulers (Quartz, EventBridge) or need calendar semantics we do not ship in a tiny client bundle. You still get a clear error instead of a silent wrong answer. For “what does this string mean?” across platforms, use the dialect table above and the official docs for your cloud.
If you are sizing recurring AI workloads, combine this tool with our token counter (rough payload size) and cost calculator (monthly scenarios vs plan caps). CloudyBot’s product surface is cloudybot.ai; scheduled tasks and Specialist duties use five-field UTC cron on the backend — the vocabulary you learn here is the same vocabulary the product uses.
Common use cases
- On-call and SRE — translate a crontab line into the next half-dozen local times before approving a change.
- Marketing automation — confirm a weekday morning send does not fall inside quiet hours in your brand’s timezone.
- CI migration — compare a Linux cron string with a GitHub Actions schedule before you paste into YAML.
- Runbooks — copy the stakeholder blurb or TSV next-run list straight into Notion, Slack, or a ticket.
- Two jobs, one window — use compare mode to see whether two expressions can fire in the same minute.
- CloudyBot scheduling — learn the schedule language, then open the dashboard and let CloudyBot run the task or assign a Specialist duty.
You know the schedule. CloudyBot can run it.
Say “Remind me every weekday at 9am to check email” and CloudyBot can create the recurring task — no cron required in chat. Or assign it as a Specialist duty: a personalised AI agent with its own name, persona, and recurring jobs that runs proactively on your behalf.
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Frequently asked questions
Is this cron schedule helper free?
Yes. There is no signup. Parsing, validation, and next-run preview run entirely in your browser.
Why don't my cron run times match AWS or GitHub?
Different platforms use different field counts and rules. Linux crontab uses five fields. AWS EventBridge and Quartz often use six or seven fields with symbols like ? and L. This page previews standard five-field expressions and links to official docs for other engines.
Is this as accurate as crond on my server?
We implement a documented subset of five-field cron with standard day-of-month versus day-of-week rules. Unsupported tokens such as L, W, or # will show a validation error for next-run preview. Always verify in your target environment before production.
Does my expression get sent to CloudyBot?
No. Parsing and next-run math run entirely in your browser. We do not put your expression in the URL hash.
What does */15 mean in the minute field?
It means every 15 minutes: minutes 0, 15, 30, and 45 each hour when other fields allow. Step values must divide evenly into the field range for our preview.
Why is DST relevant?
Cron fields are wall-clock labels in the timezone you select. When daylight saving time starts or ends, local times can skip or repeat, which shifts when a job runs relative to UTC. The next-run list uses your chosen IANA zone so you can spot risky windows.
What is a Specialist?
A Specialist is a personalised AI agent with its own name, persona, and recurring duties. Duties use five-field cron. You can describe schedules in plain English in chat; CloudyBot sets up tasks or Specialist duties in the dashboard — this tool does not configure your account by itself.
Related tools and reading
Tell it when and what. CloudyBot handles the rest.
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