JSON Validator
Paste your JSON on the left. We parse it locally and tell you immediately whether it is valid — and if not, exactly what went wrong and where.
How to use this tool
Paste your JSON into the input on the left.
If your JSON is valid, you will see a green "✓ Valid JSON" indicator and a beautified version on the right for reference.
If invalid, a clear error message appears describing the syntax problem (unexpected token, trailing comma, unterminated string, etc.).
Common causes of invalid JSON: single quotes instead of double quotes, trailing commas, unquoted keys, comments (JSON does not allow them), and control characters in strings.
Validation is local and instant — perfect for checking API payloads, config files, or copy-pasted snippets.
Frequently asked questions
What makes JSON invalid?
The usual suspects: single quotes instead of double quotes, unquoted object keys, trailing commas, JSON comments (// or /* */ — not allowed), and unescaped control characters in strings. The error message will tell you which one.
Does this support JSON5 or JSONC?
This validator targets standard JSON (RFC 8259). JSON5/JSONC features like comments and unquoted keys will report as errors — by design, since the goal is to tell you whether strict JSON parsers will accept your document.
How is this different from a JSON Schema validator?
This tool checks that your document is well-formed JSON (syntax). A schema validator additionally checks that the structure and values match a contract (semantics). Use this first; use the schema validator when you also need contract checking.
Can I validate large files?
Yes — up to tens of megabytes parse in well under a second in modern browsers. There is no server limit because nothing is uploaded.
Is my data sent anywhere?
No. Parsing happens entirely in your browser.