JSON Schema Validator - Free Online Tool

Validate any JSON document against a Draft-07 JSON Schema. Checks types, required fields, patterns, min/max values, and additionalProperties. Instant results.

JSON Data to Validate

JSON Schema (Draft-07) Generate Schema

Browser only - nothing sent to server

How to Validate JSON Against a Schema

Paste your JSON dataThe JSON document you want to validate against a schema

Paste your JSON SchemaDraft-07 schema - generate one from sample JSON if you don't have one

Click ValidateSee ✅ Valid or a detailed list of errors with property paths

JSON Schema Validator - Exact Error Paths, Not Vague Messages

Paste your JSON document and its schema side by side. The validator walks every property against every schema rule and returns precise error messages: which field failed, what type was expected, what was actually found, and the full JSON Pointer path (like /users/0/email) pointing to the exact failure location.

When an API returns a 422 Unprocessable Entity, the error message is often "Invalid request body" - technically true but useless for debugging. This validator shows you exactly which field failed validation and why, so you can fix the payload or the schema in seconds rather than minutes.

Validation Rules Checked

Type validation for all six JSON types (string, number, integer, boolean, object, array, null). Required field presence. minLength and maxLength for strings. Minimum and maximum for numbers. pattern (regex) matching on strings. enum and const constraint checking. Array minItems, maxItems, and uniqueItems rules. allOf, anyOf, oneOf, and not combiners for complex schemas. Nested object property validation recursively.

JSON Pointer Error Paths

Every error includes its JSON Pointer path: /order/items/2/price means the price field of the third item in the order's items array. This maps directly to the failing field in your JSON, making it easy to locate and fix in large documents.

When to Use Schema Validation

Before submitting API requests during development. When writing integration tests to confirm API contracts. When processing incoming webhook payloads. When validating configuration files before deployment. When checking that migrated data matches the target schema before importing.

Relevant Keywords

json schema validator, validate json against schema, json schema checker, draft-07 validation, json validation errors, json pointer, required fields validator, ajv online, api request validation, json schema testing

Frequently Asked Questions

Draft-07 is fully supported. Draft-04 and Draft-06 schemas work for most features. Draft 2019-09 and 2020-12 keywords like $dynamicRef are not yet supported - inline the referenced definitions for those schemas.

A path like /users/0/email means: the email property of the first element (index 0) of the users array. JSON Pointer (RFC 6901) uses / as a separator. Array indices are zero-based integers. ~ is escaped as ~0, / as ~1.

Yes, inline $ref references within the same document are resolved. External $ref URIs are not fetched for security - paste the referenced definitions inline or use a $defs block.

Linting checks JSON syntax - balanced brackets, valid string escaping, no trailing commas. Schema validation checks semantics - are the values the right types, are required fields present, do numbers meet min/max constraints. Both checks are separate.

400 Bad Request means the request syntax is malformed (invalid JSON, wrong Content-Type). 422 Unprocessable Entity means the syntax is correct but semantic validation failed (wrong field types, missing required fields, enum violation). Most REST APIs and the JSON:API specification prefer 422 for business validation errors.