JSON Schema Validator
Validate a JSON document against a JSON Schema (draft 2020-12) and see precise error paths and reasons.
Validation result will appear here.
JSON Schema Validator online
JSON Schema is a small vocabulary that describes the shape a JSON document is allowed to take: which properties exist, what types they hold, which ones are required, and any numeric, string or array constraints. Validating data against a schema catches mistakes early, before a malformed payload reaches an API, a database or a configuration loader. This tool runs the well-known Ajv validator entirely in your browser and reports every failure with the exact path and reason, so you can fix the data instead of guessing.
How to use this tool
- Open JSON Schema Validator in a modern browser.
- Paste a JSON Schema and the JSON data you want to check.
- Click Validate and review the status and any error paths.
- Correct the data and validate again until it passes.
Reading the result
A green status means the document satisfies the schema. A red status lists each violation on its own line, prefixed with a JSON path such as $.user.age and followed by the reason, for example must be integer or must have required property 'age'. Because the path uses dot notation from the document root, you can jump straight to the offending value even in deeply nested objects.
A worked example
Consider the schema {"type":"object","properties":{"age":{"type":"integer"}},"required":["age"]}. The instance {"age":25} passes. The instance {"age":"25"} fails at $.age because the value is a string, not an integer, and {} fails because the required property age is missing. Both the schema and the data must first be valid JSON, and this tool reports syntax errors separately from schema violations so you always know which side to fix.
Privacy and browser processing
The schema and the data are validated locally with JavaScript. Nothing is uploaded, so you can safely check configuration or API payloads that contain sensitive fields.
Frequently asked questions
What is JSON Schema?
JSON Schema is a vocabulary that describes the structure, types and constraints that a JSON document must satisfy.
Which draft is supported?
This tool validates against draft 2020-12 using Ajv v8, which also accepts most earlier drafts.
What does an error path like $.user.age mean?
The path points to the exact location in your JSON that failed validation, using dot notation from the document root.
Is my JSON uploaded?
No. Both the schema and the data are validated entirely in your browser.