{"uid":"cap_wNMJuLJLLT_8kU25E-ghZ","slug":"webbersites-date-arithmetic-api-1f16f7c7","name":"WebberSites Date Arithmetic API","description":"Exact date arithmetic — the calendar math LLMs guess at. ?from=&to= → days, business days, weeks, hours between; ?date=&add=30d|2w|3m|1y|10bd → the resulting date (bd = business days); ?date= alone → weekday, ISO week, day-of-year, leap year, unix. All UTC, Mon-Fri business days, real-calendar validation (Feb 30 is rejected).","url":"https://api.webbersites.com/api/calc/dates","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","properties":{"to":{"type":"string"},"add":{"type":"string","description":"e.g. 30d, -2w, 3m, 1y, 10bd"},"date":{"type":"string","description":"ISO date — alone: info; with add: arithmetic"},"from":{"type":"string","description":"ISO date — with to: difference"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"to":{"type":"object"},"date":{"type":"object"},"diff":{"type":"object"},"from":{"type":"object"},"result":{"type":"object"}}}}}}},"responseSchema":{"type":"json","example":{"to":{"date":"2026-12-25","weekday":"Friday"},"diff":{"days":169,"weeks":24.14,"business_days":121},"from":{"date":"2026-07-09","weekday":"Thursday"}}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","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":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_RTATmDebacaJouKJNZ6qs","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Performs exact calendar math: differences between dates (days/business days/weeks/hours), date addition/subtraction with business-day support, and date metadata lookup (weekday, ISO week, day-of-year, leap year, unix timestamp).","exampleAgentPrompt":"How many business days are there between March 15 and April 30, 2025, and what date lands exactly 10 business days after April 30?","exampleUseCases":null,"resultDescription":"A JSON object containing one or more of: diff (days, business days, weeks, hours between two dates), result (the date after adding/subtracting a duration), or date metadata (weekday, ISO week number, day-of-year, leap year boolean, unix timestamp). Invalid inputs like Feb 30 are rejected with a validation error.","failureModes":["Invalid date string (e.g. Feb 30) — rejected with a validation error","Missing required query parameters for the chosen operation mode","Malformed duration expression in 'add' parameter (e.g. unsupported unit)","Network or upstream server error returning a non-200 response"],"whenToPreferThis":"Use this endpoint whenever precise calendar math is required — especially when business-day counting, month/year offsets, or real-calendar validation (rejecting Feb 30) matter. Prefer this over asking an LLM to compute dates directly, since LLMs are prone to off-by-one errors and business-day miscounts. Ideal for scheduling, deadline calculation, SLA tracking, or any workflow requiring deterministic date results.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T00:47:22.465Z","isFirstParty":false}