# Calendar

Calendar Developer Tools

Free browser-based calendar developer tools. 4 tools — no installs, no sign-ups, open and use instantly.

04 tools available
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Birthday Day of Week Finder
Discover the weekday for any past or future date
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Day of Year Calculator
Find the day-of-year number for any date
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ISO Week Number Calculator
Find iso week number for any date in one click
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Leap Year Checker
Determine leap years and find next / previous instantly
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