All Tools VerseValidate Calendar Date
Check whether calendar dates are valid, with correct months and days, in ISO, US, or EU format.
- Runs in your browser
- Nothing uploaded
- Free, no sign-up
Processed locally in your browser. Your dates never leave this tab.
How to Use Validate Calendar Date
- Paste your dates. One per line.
- Pick the format. ISO, US, or European order.
- Validate. Each date is checked and labelled.
- Copy the result. Click Copy result. It all runs in your browser.
Frequently Asked Questions
What does it check?
That each date matches the chosen format and that the day actually exists in that month, including leap days.
Which formats are supported?
ISO as YYYY-MM-DD, US as MM/DD/YYYY, and European as DD/MM/YYYY.
What does the output show?
Each input line followed by Valid, or an explanation of why it is invalid.
Is anything uploaded?
No. The check runs entirely in your browser, so your dates never leave the tab.
Is it free?
Yes. Every tool here is free to use with no sign up.
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