Does this JSON Schema validator upload my data?

Schema parsing and instance validation run in the current browser tab. The page does not send your schema or JSON instance to a validation API.

Which JSON Schema versions are supported?

The lightweight validator covers common Draft-07 and 2020-12 keywords including type, properties, required, items, enum, const, pattern, numeric and length limits, and composition keywords. It is not a complete replacement for a standards-complete JSON Schema engine.

What is the difference between a schema error and an instance error?

A schema error means the schema itself cannot be interpreted by this validator. An instance error means the JSON data does not satisfy a valid schema keyword or constraint.

JSON Schema Validator · Browser Tool

JSON Schema Validator Online

Validate a JSON instance against a schema in your browser. See schema errors separately from instance errors, with JSON paths, approximate locations, repair hints, examples, and Markdown export.

Validate JSON How it works

Local by default: schema parsing and validation run in this browser tab. This independent lightweight validator does not upload your JSON.

SCHEMAINSTANCEPATHHINT

{ }

Separate error types

Find invalid schema rules and data mismatches independently.

Local schema workspace

Check a JSON instance against a schema.

Common Draft-07 and 2020-12 keywords are supported. This is not a complete replacement for a standards-compliant JSON Schema engine; unsupported advanced features are reported clearly.

JSON Schema

JSON Instance

Load an example or paste a schema and instance.

No validation has been run yet.

Schema errors

Schema parsing issues appear here.

Instance errors

Data constraint issues appear here.

JSON, YAML, and API testing

Validate structured payloads before testing.

Format JSON first, validate YAML fixtures, then use the result in API and test-data workflows.

JSON Formatter

Format and inspect schema or instance JSON locally.

YAML Validator

Validate YAML fixtures and convert them to JSON.

OpenAPI Validator

Inspect API contract structure and references.

API Integration Testing

Use validated payloads in browser-based API checks.

Test Data Generator

Create fictional JSON fixtures for validation cases.

JSON Diff Checker

Compare instance changes and review JSON Pointer paths.

How to validate JSON with a schema

Paste a JSON Schema and JSON Instance, or load an example.
Validate the instance to check schema syntax and data constraints separately.
Use the path and approximate location to find the failing value.
Copy or download a Markdown report for a QA ticket or test plan.

Supported keyword scope

The local checker covers common object, array, string, number, enum, const, composition, and conditional constraints. It intentionally reports unsupported advanced vocabulary instead of claiming full Draft-07 or 2020-12 compliance.

JSON Schema validator FAQ

Is validation private?

Yes, the page processes the schema and instance in the current browser tab. Avoid pasting secrets into any online tool unless your policy permits it.

Why is my schema invalid?

Common causes include a non-array required value, non-object properties, invalid regular expressions, or an impossible minimum/maximum range. Schema errors are displayed separately from instance errors.

Does this replace Ajv or another full validator?

No. It is a lightweight browser utility for common keywords and quick QA checks. Use a standards-compliant engine for production validation and advanced vocabularies.