{"uid":"cap_DWN1zTN-3ev9veQePXXMe","slug":"gregorian-date-to-iso-weekday-lookup-d4ad7a8d","name":"Gregorian Date to ISO Weekday Lookup","description":"Return the ISO weekday (1=Monday..7=Sunday) and its name for a Gregorian date.","url":"https://datetime.openverbs.com/v1/weekday","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_Z0YR0hbY-fVLbrdrwdWnF","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 weekday number (1=Monday through 7=Sunday) and its name for a given Gregorian calendar date.","exampleAgentPrompt":"What day of the week was March 15, 1990? Give me the ISO weekday number and the name.","exampleUseCases":[{"title":"Verify historical date's weekday","prompt":"What day of the week was D-Day — June 6, 1944? Give me the ISO weekday number and day name."},{"title":"Scheduling a future event","prompt":"What day of the week does December 25, 2025 fall on? I need the day name and its ISO weekday number."},{"title":"Validating a date in a form","prompt":"Can you confirm what ISO weekday number corresponds to February 29, 2000 and tell me what day it was?"}],"resultDescription":"Returns an ISO weekday integer (1=Monday through 7=Sunday) and the corresponding day name (e.g. 'Wednesday') for the input Gregorian date.","failureModes":["Invalid day value (e.g. day=32 or day=0) causes a validation error","Invalid month value (e.g. month=13) causes a validation error","Non-existent date (e.g. February 30) may return an error or be rejected","Missing required fields (year, month, or day) cause a schema validation failure","Year out of range (below 1 or above 9999) causes a validation error"],"whenToPreferThis":"Use this endpoint when you need a quick, authoritative ISO weekday number and name for any Gregorian date without doing calendar arithmetic yourself. Prefer it over general-purpose date libraries when working in a microservice or agent workflow that benefits from a dedicated, stateless HTTP call. It is ideal for scheduling logic, date validation, UI display, or any scenario where knowing the weekday of a specific date is the sole requirement.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T00:43:54.970Z","isFirstParty":false}