# JSON Schema Validator (2020-12)

> 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.

## Facts

- Endpoint: POST https://jemeen-agent-services.onrender.com/v1/validate-json?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/json-schema-validator-2020-12-2102e749
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2OIe0_K7drKMGjE4Y4-GP

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability json-schema-validator-2020-12-2102e749 -d '<json body>'
```

Example prompt: Check whether this JSON object is valid against my schema — it uses $ref, anyOf, and format constraints including email — and list every error with the exact field path and a plain-English explanation of what's wrong.

## When to prefer this

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.

## Known failure modes

- 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

## 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).

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "valid": false,
  "errors": [
   {
    "keyword": "format",
    "message": "must be a valid email",
    "schemaPath": "#/properties/email/format",
    "instancePath": "/email"
   }
  ],
  "errorCount": 1
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/json-schema-validator-2020-12-2102e749/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from jemeen-agent-services.onrender.com](https://www.zero.xyz/host/jemeen-agent-services.onrender.com/llms.txt)