JSON Validator
Check if your JSON is valid and get the exact syntax error and position if it is not — free, instant and private. Runs entirely in your browser.
100% in your browser — your data never leaves your device.
How to validate JSON
- Paste your JSON into the input box on the left.
- It is checked instantly — the status line shows Valid JSON ✓ or the exact parser error.
- If it's invalid, the error message includes the character position so you can jump straight to the problem.
- Fix the issue and re-check until the status turns green.
What JSON validation catches
JSON has a strict grammar, and small slips are easy to make by hand or
when copying from a non-JSON source. A validator parses the text with a
real JSON parser and reports the first place it breaks the spec —
common culprits include a trailing comma after the last
item in an object or array, an unquoted key (valid in
JavaScript object literals but not in JSON), a mismatched or
missing bracket — every { or [
needs a matching close in the right order — and stray single quotes
where JSON requires double quotes.
Why validate before shipping config or API payloads
Invalid JSON usually isn't caught until something downstream tries to parse it — a deploy fails on a broken config file, an API call throws on a malformed request body, or a build pipeline halts on a bad manifest. Running a quick validation pass before you commit, deploy, or send a payload catches the error while it's still cheap to fix, instead of debugging a cryptic runtime failure later.
Related tools
- JSON Formatter & Validator — pretty-print valid JSON with your choice of indentation.
- JSON Minifier — strip whitespace from JSON to get the smallest valid output.
Frequently asked questions
- Is my JSON uploaded to a server?
- No. Validation runs entirely in your browser with the native JSON parser. Your data never leaves your device.
- What errors does the validator catch?
- Anything that makes the text invalid JSON: trailing commas, unquoted or single-quoted keys, mismatched or missing brackets, unescaped control characters, and truncated input. The exact parser message and character position are shown.
- Does it validate against a schema?
- No — this checks syntax only, not structure. It confirms the text is well-formed JSON; it does not check that specific fields, types, or values match a schema like JSON Schema.
- How large a file can I validate?
- There is no fixed limit — nothing is uploaded, so the only constraint is your device's available memory. Very large files may take a moment to parse.
- What's the difference between this and the JSON Formatter?
- Both parse your JSON to check it, but the formatter also pretty-prints valid input with indentation. The validator is a quicker path when you just want a yes/no answer and the error, without needing the reformatted output.
- Why validate JSON before shipping it?
- A single stray comma or unquoted key in a config file, API response, or request body can crash a parser at runtime. Validating first catches that during development instead of in production.
- Does it modify my JSON?
- No. The validator only checks the input — it never reformats, reorders, or strips anything from what you pasted.