JSON Validator

Validate JSON and Catch Errors Fast

The JSON validator checks whether your JSON is well-formed and, if not, tells you exactly where it breaks — with the error message and the line and column. Once valid, you can format or minify it in one tap. Everything runs privately in your browser.

How to Use It

1. Paste your JSON into the text box.
2. Tap Validate to confirm it is well-formed.
3. If there is an error, read the message and location and fix it.
4. Tap Format to pretty-print, Minify to compact, or Copy to save the result.

Valid vs Invalid JSON

Valid JSON follows strict rules. Here is a quick contrast:

{ "name": "Toolzent", "free": true }   // valid
{ name: 'Toolzent', free: true, }      // invalid: unquoted key, single quotes, trailing comma

Common JSON Mistakes

Mistake	Fix
Trailing comma	Remove the comma after the last item
Single quotes	Use double quotes for keys and strings
Unquoted keys	Wrap every key in double quotes
Missing comma	Add a comma between items
Unclosed bracket	Match every {, [ with }, ]

How the Validation Works

The tool uses your browser’s built-in JSON.parse, the same engine that powers real applications. If parsing succeeds, your JSON is valid by definition. If it throws an error, the validator extracts the message and converts the character position into a human-readable line and column, so you do not have to count characters yourself.

Why It Helps

• Debug API responses that will not load.
• Fix config files for apps, build tools and CI pipelines.
• Verify generated JSON before pasting it into code.
• Clean up formatting with pretty-print or minify.

Because it all happens locally, you can safely validate sensitive payloads, tokens or configuration without anything leaving your device. Paste, validate, fix, and ship valid JSON in seconds.