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{ } JSON Formatter & Validator

Paste raw JSON to format, validate, and explore. Also convert JSON to CSV with one click.

1
Paste your JSON
2
Click Format / Validate
3
Copy clean output
JSON Input
// Formatted JSON will appear here

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data format used for storing and exchanging data. It is widely used in APIs, configuration files, and databases. Formatting makes it human-readable; validating ensures there are no syntax errors.

  • Valid JSON requires double quotes around keys and string values
  • Trailing commas are NOT allowed in standard JSON
  • Common use: REST API responses, config files, data exports
⏱️ Last Updated: June 2026 | MegaCalcOnline Editorial Team | Free browser-based tools — no upload required
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🔑 Key Takeaways

  • JSON (JavaScript Object Notation) is the most widely used data format for APIs and configs
  • Format (pretty-print) makes JSON human-readable; Minify removes whitespace for smaller files
  • All JSON keys and string values must use double quotes — single quotes are invalid
  • Trailing commas after the last item in an object or array are not allowed in JSON
  • This tool also converts JSON arrays to CSV format for spreadsheet use

JSON Formatter, Validator & Converter

Paste raw or minified JSON to format it with proper indentation, validate it for errors, or convert a JSON array to CSV format. The error validator shows the exact line and position of any syntax problems, making it easy to fix malformed JSON from APIs, config files, or data exports.

Common JSON Syntax Mistakes

ErrorWrongCorrect
Single quotes{'name': 'John'}{"name": "John"}
Trailing comma["a", "b", "c",]["a", "b", "c"]
Unquoted key{name: "John"}{"name": "John"}
Missing quotes on value{"active": true, "name": John}{"active": true, "name": "John"}

Frequently Asked Questions

What is JSON and where is it used?

JSON (JavaScript Object Notation) is a lightweight text format for storing and exchanging data. It is used in REST APIs (almost every web service API returns JSON), configuration files (package.json, settings files), databases (MongoDB stores JSON-like documents), and data exports. It is human-readable and language-independent.

Why do I get a JSON parse error?

Common causes: single quotes instead of double quotes around keys or strings; trailing commas after the last item in an array or object; unquoted property names; comments (not allowed in JSON); control characters in strings. This validator highlights the exact error location.