JSON Schema Validator
Check API payloads and config files against a JSON Schema and see every problem with its path.
- Your data never leaves your device
- 100% free
- No sign-up
- Works offline after first load
How to validate JSON against a schema
- Paste or open your JSON data on the left and the schema on the right.
- See Valid or the list of errors — click one to jump to it.
- Fix the data or the schema, or generate a schema from the data.
About JSON Schema Validator
Validate JSON data against a JSON Schema (draft 4, 7, 2019-09 and 2020-12) and see every error with its path and line.
Everything works in your browser, so it is instant and private, and your settings are remembered on this device.
Good for
- Testing API request and response contracts
- Validating config files in CI
- Writing and debugging schemas
Tip: Generate a schema from a good example, then tighten it — add minimum, maxLength and enum rules.
Frequently asked questions
Which JSON Schema versions are supported?
Draft 4, Draft 7 (also covers 6), 2019-09 and 2020-12. The version is detected from the $schema keyword, or you can choose it.
How do I read the errors?
Each error shows the keyword that failed (type, required, minimum, format…), the path in your data (like /stock/quantity) and a message. Click an error to jump to that line.
Can it create a schema for me?
Yes — click “Generate schema from data”. Types, required keys, nested objects, arrays and formats such as email, date-time, uri and uuid are detected; then adjust it to your rules.
Are formats like email and date checked?
Yes — email, date, time, date-time, uri, uuid, ipv4, ipv6, hostname and more are validated.
Is my data uploaded?
No. Everything is processed by JavaScript in your browser — nothing you paste or open is sent to a server, so it is safe for API responses, tokens, configs and customer data. It also works offline once the page has loaded.