# JSON Validator

> Validate JSON syntax and get the exact line and column of the first error, plus document statistics.

Canonical: https://host-tools.com/tools/json-validator/

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## What is a JSON validator?

A JSON validator checks whether a document is syntactically valid and, when it is not, tells you
exactly where the parser failed — line and column — instead of just "invalid JSON".

## What you get

Besides validity, this tool counts the objects, arrays, keys and characters of your document, so
you can spot structural problems at a glance. Everything runs in your browser.

## What counts as valid

This tool checks **syntax** — the rules of JSON (RFC 8259). Two consequences are worth knowing
before you trust a green check:

- **Duplicate keys are accepted.** `{"a": 1, "a": 2}` is valid JSON, and when it is parsed the last
  value wins. This tool does not flag it, so a repeated key will not show up as an error.
- **It is not a JSON Schema validator.** It confirms the document parses, not that it matches a
  shape you were expecting. Field names, types and required properties are out of scope here.

## Why a document gets rejected

These look like JSON but are not part of the specification:

- comments (`//` or `/* */`) — that is JSONC, not JSON
- a trailing comma after the last element
- single quotes instead of double quotes
- unquoted keys
- `NaN`, `Infinity` and `undefined`
- a byte order mark (BOM) before the opening brace

The reported line and column point to where the parser gave up, which is usually just after the
real mistake — so look slightly before them.