JSON Schema Validator API

About the JSON Schema Validator API

A JSON schema validator API for checking payloads before they reach your database or downstream services. JSON Schema Validator works by comparing JSON data against a JSON Schema definition you send in the same request, so you can validate JSON against a schema without bundling a validation library into every client, script or no-code workflow.

It checks types, required fields, string patterns and lengths, numeric ranges, array sizes, enums and a set of common string formats, then reports whether the document is valid and how many problems it found. Teams use it to vet webhook bodies, form submissions, config files and data imports, and to test a schema against sample records while they are still writing it.

The Free plan returns the valid flag and the error count, which is enough to accept or reject a document. Paid plans add the full error list, where each entry names the failing field path, says what rule it broke, and shows the offending value, so you can tell users exactly what to fix.

How it works

JSON Schema Validator walks your json document alongside schema recursively and records every rule that fails. It implements a focused subset of JSON Schema rather than a full draft: type (a single type or an array of types; an integer satisfies number), required and properties for objects, items with minItems and maxItems for arrays, minLength, maxLength, pattern and format for strings, minimum and maximum for numbers, and enum for any value. Keywords outside that list, such as $ref, oneOf, additionalProperties or exclusiveMinimum, are ignored rather than rejected.

When a value fails its type check, validation stops for that branch, so you get one type error instead of a cascade. Object and array rules only run when the schema's type is exactly object or array, and properties that are absent from the data are not validated unless they are listed in required. Supported formats are email, uri and url (which require an http or https prefix), date (YYYY-MM-DD), date-time and ipv4; any other format name passes. Format checks are pattern-based, so 2024-13-45 passes as a date.

valid is true when no errors were recorded and error_count is the number of errors. On paid plans, each object in errors has field (a dotted path such as user.email or items[2], or root), message, and value; type errors add expected and actual. Schema pattern regexes run in a sandbox with a two-second limit, and a pattern that exceeds it returns a 400 error. An empty object is a valid json input.

What people use it for

API Validation

Validate incoming API request payloads against defined schemas before processing to ensure data quality

Configuration Files

Verify configuration files match expected schemas before deployment to prevent runtime errors

Data Quality

Validate data integrity in ETL pipelines by checking against schemas during data transformation

Contract Testing

Ensure API responses match contract specifications by validating against JSON schemas in tests

Without writing code

JSON Validator for Windows checks your JSON and repairs it when it is broken.

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — POST /v1/jsonschemavalidator

Sent as JSON in the request body. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

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curl -X POST "https://api.apiverve.com/v1/jsonschemavalidator" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"schema":{"type":"object","properties":{"name":{"type":"string"},"age":{"type":"integer"}},"required":["name"]},"json":{"name":"John Doe","age":30}}'

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — POST /v1/jsonschemavalidator

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

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{
  "status": "ok",
  "error": null,
  "data": {
    "valid": true,
    "errors": [],
    "error_count": 0
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 2 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive JSON Schema Validator form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — JSON Schema Validator API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1