JSON Schema Validator
Paste your JSON instance on the left and a JSON Schema on the right. We validate against the schema locally and report every error with its instance path, keyword, and a human-readable message.
How to use this tool
Paste your JSON document into the left-hand box. This is the data you want to validate.
Paste a JSON Schema into the right-hand box. Draft 2020-12 is supported out of the box; older drafts mostly work too.
Click Validate. Errors appear with their JSON Pointer path (e.g. /users/0/email), the failing keyword (type, required, format…), and the relevant message.
This tool uses Ajv — the same validator that powers countless Node.js backends and OpenAPI tooling — running entirely in your browser. Common keywords are supported: type, required, properties, additionalProperties, enum, oneOf/anyOf/allOf, formats (email, date-time, ipv4, uuid, …), and more.
Because validation is local, you can safely validate API payloads, config files, or fixtures containing realistic data.
Frequently asked questions
Which JSON Schema draft is supported?
This validator targets JSON Schema draft 2020-12 via Ajv 8. Draft-07 and earlier mostly work as well, since most constructs are backwards compatible. For full draft-07 support, stick to constructs common to both.
What formats are recognized?
The standard ajv-formats set is enabled: date-time, date, time, duration, email, hostname, ipv4, ipv6, uri, uuid, json-pointer, regex, and more. Use "format" in your schema to apply them.
Why does the validator say my schema itself is invalid?
JSON Schema documents must themselves be valid JSON, and must follow the meta-schema for the draft you target. Common causes: $schema pointing at a non-existent draft, or using draft-07-only keywords with a 2020-12 $schema.
Can I use this for OpenAPI / Swagger?
Yes. OpenAPI 3.x field schemas are JSON Schema subsets. Paste the schema for a single field or response body. Full OpenAPI documents need a dedicated OpenAPI validator.
Is the validation done in my browser?
Yes. Ajv runs client-side. Neither your instance nor your schema is uploaded.