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JSON Schema Validator (2020-12)
x402
JSON Schema Validator (2020-12) is a paid API for AI agents from jemeen-agent-services.onrender.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-11-02).
Validates a JSON document against a JSON Schema (Draft 2020-12) and returns detailed errors with instance paths, schema paths, and plain-language messages.
Price / call$0.005
Success—
StatusUnknown
How this service works
Validates a JSON document against a JSON Schema (core 2020-12 keywords incl. $ref/$defs, anyOf/oneOf/allOf, formats) and returns every error with instance path, schema path and a plain-language message. Use it as an independent gate on structured LLM output before acting on it.
Output
Returns a JSON object with a boolean 'valid' field, an 'errorCount' integer, and an 'errors' array. Each error includes 'keyword' (the failing schema keyword), 'instancePath' (dot/slash path to the offending value in the document), 'schemaPath' (path to the rule in the schema), and 'message' (plain-language description of the violation).
Example use cases
LLM output gate before action
“Before you process the structured JSON that the model just returned, validate it against our user-profile schema — it has required fields, email format checks, and oneOf branches — and only proceed if there are zero errors.”
API response contract check
“I just got a JSON response from a third-party API. Can you run it against our expected response schema and tell me every field that fails, including the exact path and what rule it broke?”
Form submission data validation
“We collected this JSON form submission from a user. Validate it against our registration schema — which includes $defs for address and anyOf for phone-or-email — and give me a plain-English list of every problem so I can show it to the user.”
Technical details
Endpoint
POSThttps://jemeen-agent-services.onrender.com/v1/validate-json?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a standalone, pay-per-call JSON Schema validator that supports the full Draft 2020-12 spec including $ref/$defs, anyOf/oneOf/allOf combiners, and format keywords — especially as an independent quality gate on LLM-generated structured output before acting on it. Prefer it over inline validation libraries when you need auditability, a neutral third-party check, or when running in an environment where installing dependencies is impractical.
Side effects
- Malformed JSON input returns a parse error rather than validation errors
- Invalid JSON Schema (e.g. bad $ref target) may cause schema compilation failure
- Network timeout possible on first cold-start due to Render.com free-tier spin-up
- Missing required request fields (document or schema) return a 4xx error
- Complex schemas with deep $ref chains may hit processing limits
Output
Schema · Response
{
"type": "json",
"example": {
"valid": false,
"errors": [
{
"keyword": "format",
"message": "must be a valid email",
"schemaPath": "#/properties/email/format",
"instancePath": "/email"
}
],
"errorCount": 1
}
}Tags
x402
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