JSON Validator
Paste JSON and know instantly whether it's valid — and if not, exactly where the problem is.
● Your files are processed locally in your browser and are not uploaded to our servers.
How it works
Validation runs as you type, using the same strict parser that browsers and Node.js use (RFC 8259). When the JSON is invalid, KadiTools shows the line and column, selects the faulty line and suggests the most likely cause: trailing commas, single quotes, unquoted keys, comments or missing brackets.
FAQ
Why are comments not allowed?
Standard JSON has no comments. If your file comes from a config tool that accepts them (JSON5, JSONC), remove the comments or use the JavaScript JSON Parser.
Does it validate against a schema?
No, it checks syntax only. Schema validation may come later.