JSON Validator
Validate JSON and pinpoint the exact error line.
Paste or type JSON above — it validates as you type.
What does this tool check?
This validator runs your text through a strict JSON parser and reports exactly where it breaks — the line, the column, the offending character, and a plain-English guess at what went wrong. When the JSON is valid, it also summarizes the shape of the data: its top-level type, how many keys or items it has, how deeply nested it is, and its size in bytes.
How to validate JSON
- 1Paste your JSON into the box.
- 2Validation runs automatically about 300ms after you stop typing.
- 3A green panel means it's valid, with a quick summary of the data.
- 4A red panel shows the exact line/column, the broken snippet with a caret, and what to fix.
Common mistakes it catches
JSON is stricter than JavaScript: keys and strings must use double quotes, trailing commas before a closing bracket aren't allowed, and there's no undefined, NaN or unquoted identifiers. This tool specifically looks for these patterns near the error position so the explanation says what's actually wrong, not just where.
Frequently asked questions
›Why does it flag valid-looking JavaScript as invalid?
JSON is a stricter subset of JavaScript object literal syntax. Unquoted keys, single-quoted strings, trailing commas and comments are all valid JS but invalid JSON — this tool enforces the JSON spec exactly, the same as any JSON.parse call in production.
›What does 'depth' mean in the valid-JSON summary?
It's how many levels of nested objects or arrays the JSON contains. A flat object like {"a": 1} has depth 1; an object containing an array of objects has depth 3.
›Does validation happen as I type?
Yes, with a 300ms debounce after your last keystroke, so it doesn't re-parse on every character — that keeps things smooth even with large documents.
›Is my data sent anywhere for validation?
No. Validation runs entirely in your browser with the native JSON parser. Nothing is uploaded, which makes this safe to use on real API responses or config files with sensitive data.
›It says 'Unexpected end of JSON input' — what does that mean?
The JSON was cut off before it was complete, usually a missing closing } or ], or a value that never followed a trailing colon. Check the end of your input.