All tools

Cron Schedule Overlap Detector

Time

Find simultaneous fire times across two or more cron schedules

Paste two or more standard 5-field cron expressions and it walks minute-by-minute over a window of days to flag every minute where two or more of them would actually fire at the same time, the real question behind "will my nightly backup collide with the report job?" Each collision lists exactly which expressions matched, so you can tell a genuine simultaneous run from two jobs that just happen to look similar. It implements the same day-of-month/day-of-week OR semantics real cron does, so a schedule restricted on both fields is checked the way an actual scheduler would evaluate it, not a simplified approximation.

cronscheduleoverlapcollisiontime

How to use Cron Schedule Overlap Detector

  • 1.Enter two or more cron expressions, like a nightly backup at `0 2 * * *` and a weekly report at `0 2 * * MON`.
  • 2.Pick how many days ahead to check (7, 30, or 90) and review the list of exact collision timestamps.
  • 3.Check which expression numbers collided at each timestamp to confirm whether it's a real scheduling conflict worth staggering.

Frequently asked questions

How is this different from the Cron Next Runs tool?
Cron Next Runs previews one schedule's upcoming fire times; this tool checks two or more schedules against each other and flags the exact minutes where they'd run simultaneously.
Does it support 6-field cron with seconds?
No, only standard 5-field cron (minute, hour, day-of-month, month, day-of-week), the format crontab and GitHub Actions use.
What timezone are the results in?
Everything is computed in your browser's local time (or the server's local time for the API/SDK). If your real scheduler runs in a different timezone, translate before trusting the exact minutes shown.
Is there a limit on how many expressions or how far ahead I can check?
Up to 10 expressions at once, and a window of 1 to 365 days. At most 200 collisions are returned per check.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/cron-overlap-detector \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"expressions":["0 2 * * *","0 2 * * MON"],"windowDays":30}'

Get an API key from your dashboard · Full API docs →

Related tools

Cron Expression Generator (AI)Describe a schedule in plain English and get back a standard 5-field cron expression, a plain-English recap of when it fires, and a field-by-field breakdown, powered by GPT-4o miniTimeCron ParserParse and explain cron expressionsTimeCron Next RunsPreview the next N scheduled run times for any cron expressionTime