CronTool
Read, debug and compare cron expressions on a calendar.
Paste a cron expression and see exactly when it fires. CronTool puts several schedules side by side on one calendar, understands extended syntax, and needs no account.
What it is
See what your cron expression actually does
Cron syntax is compact and hard to read. Most mistakes are not syntax errors. They are expressions that look fine and fire at the wrong time.
CronTool shows you the exact times an expression fires, on a calendar rather than a list of timestamps. Once you can see the shape of a schedule, a wrong field is obvious.
It also puts several expressions on the same calendar, which is how you notice three separate jobs all landing at midnight. It understands extended cron syntax and needs no account.
Why it is built this way
The ideas behind it
- 01
See the times, not the syntax
An expression becomes real firing times on a calendar. A wrong field is something you can see.
- 02
Several schedules at once
Overlay cron expressions on one calendar to spot collisions before they happen.
- 03
Extended syntax
Not limited to the classic five fields, so expressions from real schedulers work.
- 04
Zero friction
Open the page, paste, read the answer. Nothing to sign up for, nothing to install.
Specifics
What you get
- Turn a cron expression into the times it will fire
- Put several cron schedules on one calendar to spot collisions
- Supports extended cron syntax, not just the classic five fields
- Edit an expression and watch the calendar update as you type
- No registration, no account, no stored state
Screens
What it looks like
A closer look at CronTool.
From tool.crontap.com
“Cron Calculator & Editor - visualize, debug & build cron expressions”
Free online cron calculator, editor and visualizer. Build, debug and read cron expressions on a calendar. Supports AWS EventBridge, Vercel cron, Quartz and standard crontab syntax.
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