JSON Schema Check

Check whether JSON data conforms to a JSON Schema for local debugging. Draft support depends on your schema's $schema field — review Ajv errors before relying on results in CI.

  • Runs entirely in your browser
  • No data stored or sent to a server
  • Free forever — no signup
  • Instant conversion

Input and Output

Use the interactive encoder and decoder on this page to process your text.

Learn more about JSON Schema validation

How to Validate JSON Against a Schema

JSON Schema Validation

When to Validate Schemas

Validate API payloads, config files, and webhook bodies against JSON Schema before deployment or integration testing. Paste your JSON instance and schema to see precise validation errors with paths.

Real-World Examples

Reject API requests where email is missing or not a string

Verify config files require version as a number before deploy

Catch webhook payloads with unexpected extra fields using additionalProperties: false

Common Mistakes

  • Confusing JSON syntax errors with schema violations — parse JSON first
  • Using draft-04 keywords in a draft 2020-12 schema (or vice versa)
  • Expecting automatic type coercion — "42" is a string, not a number

Developer Tips

  • Store schemas in version control alongside OpenAPI specs
  • Use required arrays for mandatory fields, enum for allowed values
  • Run schema validation in CI for config and fixture files

Frequently asked questions

Is this the same as JSON syntax validation?

No. Syntax validation checks whether text parses as JSON. Schema validation checks whether parsed data matches your declared structure and types.

Which JSON Schema draft is supported?

This tool uses Ajv, which supports modern JSON Schema drafts. Check your schema $schema field for compatibility.

How do I read validation errors?

Each error includes a JSON Pointer path (e.g. /user/email) and a message describing the failed constraint.