{"uid":"cap_hN_fYhvAIVUNg07ac5Hqm","slug":"iso-week-number-lookup-8fc7bd91","name":"ISO Week Number Lookup","description":"Return the ISO-8601 week-numbering year, week number (1..53) and weekday (1=Monday..7=Sunday) for a Gregorian date. The ISO year can differ from the calendar year around New Year.","url":"https://datetime.openverbs.com/v1/iso-week","method":"POST","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method","bodyType","body"],"properties":{"body":{"type":"object","required":["year","month","day"],"properties":{"day":{"type":"integer","maximum":31,"minimum":1},"year":{"type":"integer","maximum":9999,"minimum":1},"month":{"type":"integer","maximum":12,"minimum":1}},"additionalProperties":false},"type":{"type":"string","const":"http"},"method":{"enum":["POST"],"type":"string"},"bodyType":{"enum":["json","form-data","text"],"type":"string"}},"additionalProperties":false}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.004","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.004/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_KOoRr1QpZvh8pFF1RPk88","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.004","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Returns the ISO 8601 week-numbering year, week number (1–53), and weekday (1=Monday…7=Sunday) for a given Gregorian calendar date.","exampleAgentPrompt":"What ISO week number does December 30, 2024 fall in, and which weekday is it? I want the ISO week-numbering year too since it might differ from the calendar year.","exampleUseCases":[{"title":"Year-end payroll week assignment","prompt":"Our payroll system uses ISO week numbers — can you tell me which ISO week and ISO year December 31 2024 belongs to? I need to know if it's week 53 of 2024 or week 1 of 2025."},{"title":"Sprint planning date alignment","prompt":"We label our sprints by ISO week number. What ISO week number is January 6 2025, and is it a Monday? I need the weekday number too."},{"title":"Reporting period boundary check","prompt":"I need to confirm which ISO week number March 31 2026 falls in, and what day of the week it is — our quarterly reports are organized by ISO week."}],"resultDescription":"Returns the ISO week-numbering year (which may differ from the Gregorian calendar year near New Year's), the ISO week number (1–53), and the ISO weekday number (1=Monday through 7=Sunday) for the supplied date.","failureModes":["Invalid month value (e.g. 13) returns a validation error","Day out of range for the given month returns an error","Missing required field (year, month, or day) returns a 400-level error","Non-integer or out-of-range year (outside 1–9999) rejected by schema"],"whenToPreferThis":"Use this endpoint when you specifically need ISO 8601 week-date components — especially around New Year when the ISO week-numbering year diverges from the Gregorian year. Prefer it over ordinal-day or weekday-only endpoints when you need all three ISO week-date fields (year, week, weekday) together in one call.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T00:44:58.053Z","isFirstParty":false}