JSON Schema Validator Online
Validate JSON data against a JSON Schema. Catch errors instantly with detailed error messages and paths.
Need a schema? Generate one from JSON
JSON Data
JSON Schema
About JSON Schema Validator
Validate your JSON data against a JSON Schema to ensure it meets your defined structure, types, and constraints. Our validator uses the industry-standard Ajv engine to provide instant, detailed validation results — showing exactly where and why your data fails. Perfect for API contract testing, CI/CD pipelines, form validation debugging, and data quality assurance.
How to Use JSON Schema Validator
Paste Your JSON Schema
Paste your JSON Schema definition into the left editor panel, or drag and drop a .json schema file. The validator auto-detects the draft version from the $schema URI. If you do not have a schema yet, use our JSON Schema Generator to create one from sample data.
Paste the JSON Data to Validate
Paste the JSON data you want to validate into the right editor panel, or drag and drop a data file. This is the actual payload, configuration, or document you want to check against the schema rules.
Review Validation Results
Click Validate and instantly see the results. Valid data shows a green success indicator. Invalid data lists every error with the exact instance path (where in your data), the schema path (which rule failed), and a human-readable message explaining the violation.
Common Use Cases
API Contract Testing
Validate API responses against your schema to ensure they match the expected contract. Catch breaking changes, missing fields, and type mismatches during development before they reach production or affect consumers.
Configuration File Validation
Verify that configuration files like package.json, tsconfig.json, CI/CD pipeline configs, and Terraform variables conform to their expected schema. Catch structural errors before deployment.
Data Quality Assurance
Validate data imports, ETL pipeline outputs, and database exports against schemas to ensure data integrity and consistency. Especially useful when ingesting data from third-party sources or partners.
Form Validation Debugging
Test and debug JSON Schema-based form validation rules used by libraries like Ajv, react-jsonschema-form, or Formik. See exactly which fields fail and why to quickly fix schema definitions.
Schema Development and Testing
Iteratively develop JSON Schema definitions by testing them against various sample payloads. Quickly verify that your schema accepts valid data and rejects invalid data before deploying it to production validators.
Webhook Payload Verification
Validate incoming webhook payloads from services like Stripe, GitHub, or Twilio against your expected schema to ensure your handler code will receive the data structure it expects.
Why Use Our JSON Schema Validator?
Instant Feedback
See validation results immediately with detailed, actionable error messages and exact paths
Industry Standard Engine
Powered by Ajv, the fastest and most widely adopted JSON Schema validator in the JavaScript ecosystem
Detailed Error Reporting
Get exact instance paths, schema paths, and human-readable messages for every single violation
Full Format Support
Validates format keywords like email, uri, date, date-time, ipv4, uuid, and more via ajv-formats
All Errors at Once
Runs in allErrors mode so you see every issue in a single pass, not just the first one
Privacy-First
Both your schema and data stay in your browser. Nothing is uploaded, logged, or stored on any server
Key Features
Powered by Ajv — the fastest JSON Schema validator in the JavaScript ecosystem
Supports Draft-07 and Draft 2020-12 specifications
Detailed error messages with instance paths showing exactly where errors occur
Schema path references for each error pointing to the exact rule that failed
allErrors mode — reports every violation in a single pass, not just the first
Format validation (email, uri, date, date-time, ipv4, ipv6, uuid) via ajv-formats
File upload with drag and drop support for both schema and data panes
Auto-detection of JSON Schema draft version from $schema URI
Direct link to JSON Schema Generator for quick schema creation
Syntax-highlighted Monaco editors with real-time JSON validation
100% Client-Side Processing
Your data never leaves your browser
All processing happens in your browser using JavaScript. Your data is never sent to our servers or any third party. Safe for sensitive data, API keys, and production configs.
Frequently Asked Questions
Quick answers to common questions about json schema validator
JSON Schema validation checks your JSON data against a schema definition that describes the expected structure. The schema defines property names, data types (string, number, boolean, etc.), required fields, value constraints (minimum, maximum, pattern), and nested structures. Our validator compares your data against every rule and reports all violations with exact paths and messages.
We use Ajv (Another JSON Schema Validator), the fastest and most widely-used JSON Schema validator in the JavaScript ecosystem. Ajv is used by millions of projects including webpack, ESLint, and many API frameworks. It supports Draft-07 and Draft 2020-12 specifications with full compliance.
Each error includes two paths. The instance path (e.g., /address/city) shows exactly where in your JSON data the error occurred. The schema path (e.g., #/properties/address/properties/city/type) shows which schema rule was violated. Together, they let you pinpoint exactly what went wrong and which schema constraint to adjust.
Yes. Our validator supports both Draft-07 and Draft 2020-12 schemas. It auto-detects the version from the $schema URI in your schema definition. If no $schema is specified, it defaults to Draft-07 for maximum compatibility.
You have several options: use our JSON Schema Generator tool to automatically create a schema from sample JSON data, check OpenAPI/Swagger documentation for API schemas, browse SchemaStore.org for common configuration file schemas, or write your own schema following the JSON Schema specification.
Yes. With ajv-formats enabled, our validator checks format keywords including "email", "uri", "url", "date", "date-time", "time", "ipv4", "ipv6", "uuid", "hostname", "json-pointer", and "regex". These format checks ensure strings match expected patterns beyond basic type checking.
The validator runs in allErrors mode, which means it checks every rule in your schema and reports all violations in a single pass. This is more efficient than fixing errors one at a time — you can see the complete list of issues and address them all before re-validating.
Absolutely. The validator handles deeply nested schemas with items (for arrays), properties (for objects), additionalProperties, patternProperties, oneOf, anyOf, allOf, and all other JSON Schema composition keywords. Errors in nested structures include the full path from root to the failing value.
Yes. You can paste your OpenAPI schema component and test it against actual API response payloads. This is a common workflow for API contract testing — validate that your API returns the shape of data your clients expect, catching regressions before they ship.
Learn More
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JSON Schema Explained: A Practical Guide
Learn what JSON Schema is, how it works, and best practices for validation
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Fix Common JSON Errors
Troubleshoot common JSON syntax errors before running schema validation
=> { }
JSON API Best Practices
Design APIs with proper schema contracts and response validation
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