JSON Validator

Free online JSON validator. Checks whether JSON is valid and reports its type and size. Parse errors are located to the exact line and column. Runs entirely in your browser.

Runs locally · data never uploaded
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How to use

What it does

A JSON validator confirms whether a piece of text is valid JSON. This tool tells you not only "valid or not", but also, when valid, the data type, character / byte size and the shape of objects or arrays. When invalid, it pinpoints the error to the exact line and column instead of a vague "format error".

Example

Input:

{
  "name": "DevUtils",
  "tools": 36,
  "local": true
}

Result:

✓ Valid JSON

Type: object
Characters: 56
Bytes: 56
Top-level keys: 3

If you write {name: 1} (missing quotes around the key), it will report an error near "line 1, column 2".

Common mistakes

  • Keys must be wrapped in double quotes
  • No trailing comma after the last item of an array or object
  • Single quotes and // comments are not allowed
  • Quotes inside strings must be escaped

Validation happens entirely in your browser and works offline.

FAQ

Q1.Why can errors be located to a line and column?
The browser JSON parser stops at the offending character and reports a character offset, which this tool converts into line and column numbers pointing straight at the problem.
Q2.How large a JSON can it handle?
Parsing runs in the browser, so anything up to a few tens of megabytes usually works; for very large files prefer a command-line tool.
Q3.Does passing validation mean the data is correct?
No. Validation only confirms syntax is legal, not field meaning, value ranges or business rules — you still need domain checks afterwards.
Q4.Is my JSON uploaded?
No. Parsing happens entirely in your browser, and the tool works offline.
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