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Free Online JSON Validator & Formatter

This JSON validator lets you check, format, and debug JSON data directly in your browser. Whether you are building a REST API, configuring a cloud service, or debugging a webhook payload, paste your JSON and get instant results with precise error locations. No signup, no server uploads — your data stays in your browser.

Instant Validation

Check JSON syntax in milliseconds with exact error line and column numbers.

Prettify & Minify

Beautify JSON with indentation or compress to a single line.

Syntax Highlighting

Color-coded output for keys, strings, numbers, booleans, and nulls.

100% Private

All processing happens client-side. No data is sent to any server.

28 Languages

All 24 official EU languages plus Chinese, Vietnamese, Farsi, and Hindi.

Keyboard Shortcuts

Press Ctrl+Enter (Cmd+Enter on Mac) to validate instantly.

How to Validate JSON

Paste your JSON into the left panel, click Validate (or Ctrl+Enter), and view the result. Valid JSON appears syntax-highlighted. Invalid JSON shows the error with exact line and column. Use Prettify to indent, Minify to compress, and Copy to clipboard.

Common Use Cases

REST API responses, configuration files (package.json, tsconfig.json), database exports, webhook payloads, and data migration scripts. Catches missing commas, unmatched brackets, trailing commas, and incorrect escaping.

Frequently Asked Questions

What is a JSON validator?
A JSON validator checks whether a text string is valid JSON according to the ECMA-404 standard. It parses the input and reports syntax errors with their exact location.
How do I validate JSON online?
Paste your JSON text into the input panel, then click Validate or press Ctrl+Enter. The tool shows a success message or a detailed error with exact line and column.
What is the difference between prettify and minify?
Prettify adds indentation and line breaks for readability. Minify removes all whitespace for the smallest output, ideal for production.
Is this JSON validator free?
Yes, completely free with no registration. All processing happens in your browser.
What languages are supported?
28 languages: all 24 official EU languages plus Chinese, Vietnamese, Farsi, and Hindi.
What common JSON errors does this catch?
Missing or extra commas, unmatched brackets or braces, unquoted keys, single-quoted strings, trailing commas, invalid escape sequences, and incorrect null/true/false usage.