Keyronne JSON Schema Validator & LLM Output Coercer

x402

Keyronne JSON Schema Validator & LLM Output Coercer is a paid API for AI agents from keyronne.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-10).

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.

Price / call$0.001

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StatusUnknown

How this service works

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"}}

Output

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.

Example use cases

Example prompt

“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?”

Technical details

Endpoint

POSThttps://keyronne.com/api/validate-json?utm_source=zero.xyz

When to prefer

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.

Side effects

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

Input

Schema · Request body

Field	Type	Description
data	—	The candidate JSON value to validate and coerce.
coerce	boolean	Attempt type coercion and default-filling before validating.
schema	object	JSON Schema (draft-07 style subset: type, properties, required, items, enum, const, additionalProperties, min/max constraints, pattern, default).

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