Free Online JSON Validator
Check whether your JSON is valid, pinpoint syntax errors with line numbers, and validate against a JSON Schema, all in your browser.
No sign-up to start · Runs in your browser
How to validate JSON
- 1
Paste your JSON
Add the JSON you want to check into the editor. Syntax errors are flagged immediately with line-level messages.
- 2
Add a schema (optional)
Open the Schema panel and paste a JSON Schema to validate structure, required fields, types, and formats.
- 3
Fix and re-check
Jump to each error, correct it, and watch validation update live until your JSON is valid.
Why validate with JSON Copilot
Real-time syntax checks
Errors are detected as you type, with the exact line and cause.
JSON Schema validation
Validate against Draft-07 schemas: required fields, types, enums, and formats.
Client-side & private
Validation runs locally; your JSON is never uploaded.
Clear error messages
Human-readable messages help you fix problems fast.
Frequently asked questions
How do I know if my JSON is valid?
Paste it into the editor. JSON Copilot validates instantly and shows a success message, or flags the exact line and reason if something is wrong.
Can I validate against a JSON Schema?
Yes. Open the Schema panel and paste a Draft-07 JSON Schema; JSON Copilot checks required fields, types, formats, and constraints, listing every violation.
Is the validator free and private?
Yes. Validation is free, needs no account, and runs entirely in your browser. Your data never leaves your device.