{"uid":"cap_gIqp897i-oHHGr6Djas2Q","slug":"fastapi-online-json-schema-validation-c910a9aa","name":"fastapi.online — JSON Schema Validation","description":"Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding & crypto utilities, date/time calculators, geo/coordinate math, math & finance calculators, novelty tools, and business/social writing generators — 179 endpoints in all, across multiple specialized self-hosted models. Pay per call with crypto — no signup — or get an API key.","url":"https://api.fastapi.online/validate-json?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"data":{},"schema":{"type":"object"}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.0005","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":"down","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.0005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.0005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.0005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_vfrfh5idtkn8jZlHj6Rq5","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.0005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Validates a JSON string against a provided JSON Schema and returns whether it is valid","exampleAgentPrompt":"Can you check if this JSON string '{\"name\":\"Alice\",\"age\":30}' is valid against this schema: {\"type\":\"object\",\"required\":[\"name\",\"age\"],\"properties\":{\"name\":{\"type\":\"string\"},\"age\":{\"type\":\"integer\"}}}?","exampleUseCases":[{"title":"API payload pre-flight check","prompt":"Before I send this JSON payload to the orders API, validate it against this schema to make sure it won't be rejected: data is '{\"orderId\":\"abc123\",\"quantity\":2}' and the schema requires orderId as a string and quantity as an integer."},{"title":"Config file format enforcement","prompt":"Check whether this config JSON string '{\"timeout\":30,\"retries\":\"three\"}' is valid against my schema that requires both fields to be integers — I suspect there's a type error."},{"title":"User-submitted form data verification","prompt":"A user just filled out a registration form and the output is this JSON: '{\"email\":\"user@example.com\",\"age\":25}' — can you validate it against my schema that requires email as a string and age as a number before I save it?"}],"resultDescription":"Returns a JSON object with a 'valid' boolean field indicating whether the provided data string conforms to the given schema. May include additional fields describing validation errors or details when invalid.","failureModes":["Malformed JSON data string causes parsing error","Invalid or unparseable schema object returns error","Missing required 'data' or 'schema' fields returns 400","Schema references unsupported JSON Schema features and validation fails unexpectedly","Payment not processed (402) if no API key and crypto payment fails"],"whenToPreferThis":"Choose this endpoint when you need a quick, lightweight, pay-per-call JSON Schema validation without signup. Ideal for agents that occasionally need to validate JSON payloads against schemas without provisioning a dedicated validation service. Avoid if you need deeply nested $ref resolution or complex JSON Schema draft versions beyond what the service supports.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-22T01:28:32.183Z","isFirstParty":false,"canonicalSlug":"fastapi-online-json-schema-validation-c910a9aa"}