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JSON Linter

Validate, format, and beautify your JSON code instantly. Detect and fix syntax errors with real-time validation.

Input

0 characters1 lines

Output

Output will appear here...

0 characters1 lines

Features

Real-time Validation

Instantly detects and highlights JSON syntax errors as you type.

Format & Beautify

Automatically formats your JSON with proper indentation.

100% Client-Side

Your JSON never leaves your browser. Complete privacy.

Common Use Cases

// API Response
{
  "status": "success",
  "data": {...}
}
// Configuration
{
  "app": {
    "name": "MyApp",
    "version": "1.0.0"
  }
}

100% Client-Side Processing

Your data never leaves your browser. Zero server processing, zero tracking.

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About the Json Lint

Validate and format JSON online for free. Paste any JSON to find syntax errors with their exact location, beautify minified payloads, and lint config files - fast and private, with all parsing running in your browser and nothing uploaded.

Invalid JSON is one of the most common causes of broken API integrations, failing CI pipelines, and crashed configs. A single trailing comma, unquoted key, or unmatched bracket is all it takes — and the error message from your database or runtime rarely tells you where.

Paste any JSON to validate it instantly, with the exact error position highlighted. Valid JSON is beautified into a readable, indented form. Your payloads never leave the browser, so it is safe to paste production data, tokens, and private configs.

Use cases and examples

Diagnose a failing CI pipeline: paste the JSON config and jump straight to the trailing comma or unquoted key the error message never mentioned.

Beautify minified API responses so you can read the structure before writing code against them.

Check JSON5-style config files that permit comments before stripping them for strict parsers.

How to use

  1. Paste your JSON into the editor.
  2. Syntax errors are flagged instantly with their location.
  3. Valid JSON is automatically formatted and indented.
  4. Copy the cleaned result or minify it for production use.

Frequently Asked Questions

Does the validator support comments in JSON? ▾

Yes, JSON5-style comments are accepted so you can validate config files that include them. Standard JSON must be comment-free, and the validator tells you when a comment is the only issue.

Is this tool free to use? ▾

Yes! This tool is 100% free. No signup, no credit card, no limits. It's part of Formatho's privacy-first developer toolkit.

Is my data safe? Does this tool send data to a server? ▾

Absolutely. This tool runs entirely in your browser. Your data never leaves your device. Zero server-side processing, zero tracking.