How to validate JSON against a JSON Schema

API contracts live in JSON Schema; payloads drift. The JSON Schema Validator checks instance data against your schema and lists every mismatch.

How it works

1. JSON instance — the data to validate.
2. JSON Schema — draft-compatible schema document.
3. Review errors — path and message per failure.

When to validate

Validate webhook payloads, config files, and API responses before they hit production pipelines.

Format first

Clean up JSON with the JSON Formatter if parsing fails.

The How to validate JSON against a JSON Schema is free, runs locally, and never sends your data to a server. More developer tools at maratool.com.