{"uid":"cap_XHid0JUs3M5QuhSqGBajZ","slug":"calendar-systems-leap-year-checker-49c327a1","name":"Calendar Systems – Leap Year Checker","description":"Is a year a leap year in the Gregorian, Julian, Hebrew, Islamic (tabular) or Persian calendar? 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Also tell me which leap years are nearby and what rule applies.","exampleUseCases":[{"title":"Historical date accuracy check","prompt":"Was 1700 a leap year in the Gregorian calendar versus the Julian calendar? I'm trying to figure out if a historical document date would shift between Old Style and New Style."},{"title":"Hebrew calendar leap year lookup","prompt":"Is Hebrew year 5784 a leap year? I need to know the rule used and what the next and previous leap years are in the Hebrew calendar."},{"title":"Persian calendar leap year verification","prompt":"Is the Persian year 1403 a leap year? Tell me the leap rule and the surrounding leap years in the Persian Solar Hijri calendar."}],"resultDescription":"Returns a boolean leapYear verdict, the calendar-specific rule as a string, a plain-language summary, the number of days in the year, the previous and next leap years, the leap cycle name, and optional disclaimer or degraded-mode flags.","failureModes":["Missing required 'year' parameter returns an error","Invalid calendar enum value (not one of gregorian/julian/hebrew/islamic/persian) returns a validation error","Extremely large or small year values may return degraded results or null fields","Non-integer year values will fail schema validation"],"whenToPreferThis":"Use this endpoint when you need calendar-system-specific leap year logic beyond just the Gregorian calendar — particularly for historical dates under the Julian calendar, Jewish/Hebrew calendar computations, Islamic tabular calendar scheduling, or Persian Solar Hijri date arithmetic. It also provides adjacent leap years and rule explanations, making it ideal for educational or historical research contexts rather than a simple yes/no check.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-29T13:11:12.779Z","isFirstParty":false,"canonicalSlug":"calendar-systems-leap-year-checker-49c327a1"}