JSON Schema Validator

What is JSON Schema?

JSON Schema is a vocabulary for describing the structure, types, and constraints of JSON data. A schema can require certain properties, restrict values to specific types, enforce minimum and maximum numbers, validate string formats like email addresses, and much more. It is the standard way to document and enforce the shape of JSON used by APIs and configuration files.

Our JSON Schema Validator is powered by Ajv, the most widely used JSON Schema engine in the JavaScript ecosystem. It compiles your schema and validates your data against it, collecting every violation rather than stopping at the first one.

How to Validate JSON

• Paste your JSON Schema into the left pane, or click Sample for an example
• Paste the JSON data to check into the right pane
• Validation runs instantly — a green banner confirms valid data
• If the data is invalid, each error is listed with its path and reason
• Errors in the schema or data JSON itself are reported separately and clearly

Understanding Validation Errors

Each validation error shows an instance path — pointing to the exact location in your data that failed, such as /age or /address/zip — alongside a human-readable message like must be >= 0 or must have required property 'name'. This makes it straightforward to locate and fix problems even in large, deeply nested documents.

Because all errors are collected at once, you can fix every issue in a single pass instead of repeatedly re-running validation after each individual fix.

Who Uses a JSON Schema Validator?

API developers use it to verify that request and response bodies conform to their documented contracts. DevOps engineers validate configuration files before deployment to catch mistakes early. QA engineers build it into test suites to guard against regressions. Everything runs locally in your browser, so your schemas and data stay completely private.