{"uid":"cap_anzB0Q50hP8zWBUQvd5Gr","slug":"keyronne-json-schema-validator-llm-output-coercer-aa2e280e","name":"Keyronne JSON Schema Validator & LLM Output Coercer","description":"Validate a JSON value against a JSON Schema and coerce common LLM-output mistakes (numbers as strings, stringified booleans, scalars where arrays are expected, missing defaults, extra properties). Returns the coerced value plus a structured error report. Built for cleaning up LLM tool-call arguments and structured outputs. POST a JSON body like: {\"schema\":{\"type\":\"object\",\"required\":[\"name\",\"age\"],\"properties\":{\"name\":{\"type\":\"string\"},\"age\":{\"type\":\"integer\"}}},\"data\":{\"name\":\"Ada\",\"age\":\"36\"}}","url":"https://keyronne.com/api/validate-json?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"data":{"description":"The candidate JSON value to validate and coerce."},"coerce":{"type":"boolean","default":true,"description":"Attempt type coercion and default-filling before validating."},"schema":{"type":"object","description":"JSON Schema (draft-07 style subset: type, properties, required, items, enum, const, additionalProperties, min/max constraints, pattern, default)."}}},"responseSchema":null,"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":{"p10Cents":"0.1000","medianCents":"0.1000","p90Cents":"0.1000","minCents":"0.1000","maxCents":"0.1000","p95Cents":"0.1000","sampleCount":1,"varies":false,"failureChargeRate":1},"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_88wzmqO7_9uua9XRZESvC","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":"Validates a JSON value against a JSON Schema and automatically coerces common LLM output mistakes (numbers as strings, stringified booleans, missing defaults, extra properties) before returning a corrected value and structured error report.","exampleAgentPrompt":"My LLM returned {\"name\":\"Ada\",\"age\":\"36\"} but the schema requires age to be an integer — can you validate it against the schema {\"type\":\"object\",\"required\":[\"name\",\"age\"],\"properties\":{\"name\":{\"type\":\"string\"},\"age\":{\"type\":\"integer\"}}} and coerce any type mismatches so I get back a clean, corrected value?","exampleUseCases":null,"resultDescription":"Returns the coerced/corrected JSON value (with type fixes applied, defaults filled, extra properties stripped) plus a structured error report listing any fields that could not be coerced, constraint violations, and a summary of what was changed.","failureModes":["Schema itself is invalid — returns error describing the schema parsing failure","Data cannot be coerced to the required type (e.g. a non-numeric string where an integer is required) — reported in the error section with the offending field path","Missing required fields that have no default and cannot be inferred — flagged in the error report","Malformed request body (missing schema or data fields) — returns 400-level error","Unsupported JSON Schema keywords outside the supported draft-07 subset — may be silently ignored or flagged"],"whenToPreferThis":"Use this endpoint whenever an LLM or AI agent returns structured output (tool-call arguments, function parameters, or JSON responses) that needs to be validated and lightly repaired before downstream use. Ideal when the LLM frequently makes type coercion mistakes like returning numbers as strings or booleans as 'true'/'false' strings. Prefer this over a generic JSON validator when you also need auto-coercion and default-filling, not just a pass/fail result.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-10T00:51:24.460Z","isFirstParty":false,"canonicalSlug":"keyronne-json-schema-validator-llm-output-coercer-aa2e280e"}