Validate JSON against JSON Schema online.
Validate JSON payloads against Draft-07 and Draft 2020-12 JSON Schema specifications with instant client-side feedback. 100% private in-browser with zero server uploads.
JSONGlow's JSON Schema Validator is a fast, 100% client-side validation utility that checks JSON data payloads against JSON Schema definitions using Ajv, highlighting exact error paths in real time.
Overview
Why JSON Schema validation is critical for contract testing
JSON Schema is the industry-standard specification for describing the structure, required fields, constraints, and data types of JSON documents. It powers OpenAPI (Swagger) contracts, Kubernetes custom resource definitions (CRDs), configuration validation, and API payload enforcement.
When building or consuming APIs, discovering schema mismatch bugs in production leads to runtime crashes and silent data corruption. Validating your payload against its JSON Schema definition ahead of deployment guarantees that required properties, enum values, minimums, maximums, and string formats are fully satisfied. You can also check general RFC 8259 syntax using our JSON Validator or format payloads with the JSON Formatter.
Unlike cloud-hosted validators that transmit your schemas and live payload data across third-party networks, JSONGlow runs completely inside your local web browser sandbox using compiled Ajv validation routines. Your proprietary data and internal API contracts never leave your machine.
You can inspect exact JSON pointer paths for violations, test sample schemas, download validated files, or generate programmatic Zod validation schemas using our companion tools. For TypeScript schema generation, try our JSON to Zod Converter or produce static type declarations with JSON to TypeScript.
Workflow Guide
How to validate JSON against a schema in 3 steps
Input your JSON Schema
Paste your Draft-07 or Draft 2020-12 schema definition into the left editor panel.
Input the JSON data payload
Paste the JSON object or array you wish to validate into the right editor panel.
Inspect live validation results
View the instant green badge for compliant data or inspect exact line pointers for schema violations.
Practical Demonstration
JSON Schema Validation Example
See how a JSON Schema definition enforces data constraints and catches invalid payloads.
{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "object",
"properties": {
"id": { "type": "integer", "minimum": 1 },
"email": { "type": "string", "format": "email" },
"role": { "type": "string", "enum": ["admin", "developer"] }
},
"required": ["id", "email", "role"]
}{
"id": 1042,
"email": "dev@jsonglow.com",
"role": "developer"
}Troubleshooting & Edge Cases
Common schema validation violations & solutions
Missing required properties
Why it happens: The 'required' array lists properties that are missing from the input object payload.
"required": ["id", "username"]Type mismatch (string instead of integer)
Why it happens: A numeric value enclosed in quotes (e.g. "123") fails schema validation when type is set to 'integer' or 'number'.
Enum value not matched
Why it happens: Property value does not match any of the allowed literal values declared in the 'enum' array.
String format violations (email, uri, date-time)
Why it happens: Strings failing regex validation for standard formats like 'email' or 'date-time' trigger format errors.
Core Capabilities
Engineered for API contract validation & speed
Ajv-Powered Validation
Uses compiled Ajv routines for standard-compliant Draft-07 and Draft 2020-12 validation.
100% Client-Side Privacy
Zero server uploads. Schemas and sensitive payload bytes are evaluated strictly inside local browser memory.
Exact Error Pointers
Pinpoints exact JSON instance paths (e.g. /users/0/email) and violation keywords for rapid debugging.
Preset Schema Library
Quick-load sample user registration schemas and payload tests to verify validation rules.
Dual Editor Panels
Side-by-side editing allows simultaneous tweaking of schema rules and live test data payloads.
Fast Real-Time Evaluation
Validates instantly as you type with non-blocking deferred evaluation for smooth editor typing.
Frequently Asked Questions
Common questions answered.
Need more help? Our tools execute entirely in your browser without transmitting any payload to remote servers.
Which JSON Schema drafts are supported?+
JSONGlow supports modern JSON Schema drafts including Draft-07, Draft-06, Draft-04, and Draft 2020-12 powered by Ajv.
Does JSONGlow transmit my schemas or data over the network?+
No. All schema compilation and data validation happen 100% locally in your browser. No payload data is sent to external servers.
Can I generate a schema from raw JSON instead?+
Yes. If you need runtime validation code for TypeScript, use our JSON to Zod Schema Generator to create complete type-safe schemas automatically.
How are validation errors displayed?+
When a payload violates schema constraints, an alert lists each failed property with its JSON Pointer path, rule keyword (such as 'required' or 'type'), and actionable message.
Can I validate arrays of objects against a schema?+
Yes. Define the root schema with 'type': 'array' and describe individual object constraints inside the 'items' property.
Is this JSON Schema validator free?+
Yes. It is completely free with no usage limits, no credit card, and no registration required.
Explore More Tools & Guides
The JSONGlow developer kit.
JSON Validator
Live strict RFC 8259 syntax checker pointing to exact line and column coordinates of malformed tokens.
JSON to Zod Schema
Generate production-grade Zod validation schemas & TypeScript types with one-click .ts download.
JSON Formatter
Format, beautify, indent, sort keys alphabetically, and inspect nested JSON structures.