JSON Validator – Check JSON Syntax Online

Invalid JSON is one of the most frustrating debugging experiences — the error message rarely tells you exactly which line is wrong. A JSON validator checks your JSON for syntax errors and tells you precisely what's broken.

Why JSON Validation Matters

JSON has strict syntax rules. One misplaced comma or unquoted key breaks the entire document. Common errors include:

- **Trailing comma**: `{"name": "Rohith",}` — comma after the last key

- **Single quotes**: `{'name': 'Rohith'}` — JSON requires double quotes

- **Unquoted keys**: `{name: "Rohith"}` — all keys must be quoted strings

- **Missing comma**: `{"a": 1 "b": 2}` — items must be separated by commas

- **Comments**: `// this is invalid` — JSON does not support comments

How to Validate JSON

Paste your JSON into DevConvert. The converter auto-detects the format and shows you:

1. Whether the JSON is valid

2. The formatted (pretty-printed) output if it's valid

3. Where the error is if it's invalid

Example: Fixing Invalid JSON

Invalid input:

{

'id': 1,

name: "Rohith",

active: True,

}

Problems:

- Single quotes on `'id'`

- Unquoted key `name`

- Python boolean `True` instead of JSON `true`

- Trailing comma after last value

Valid JSON output:

{

"id": 1,

"name": "Rohith",

"active": true

}

When to Validate JSON

- Before sending API requests in Postman or Insomnia

- After copying JSON from a browser console or log file

- When debugging a `SyntaxError: Unexpected token` in JavaScript

- Before importing config files into tools that require strict JSON

DevConvert validates and formats your JSON in the same step — paste, convert, done.