Toolvantas

Developer utility

JSON Formatter and Validator

Clean, indent, validate, sort, and minify your JSON data instantly. Detect syntax errors safely, inspect payload size and object key counts, and export clean JSON locally in your browser.

Ready for input0 chars
Original Size0 B
Output Size0 B
Object Keys0

What is JSON formatting and validation?

JavaScript Object Notation (JSON) is the standard data interchange format for REST APIs, configuration files, and document stores. Over networks, JSON is often minified into a single line to save bandwidth.

  • Beautification: Restores readable hierarchy, line breaks, and consistent indentation (2 spaces, 4 spaces, or tabs) for debugging.
  • Validation: Checks strict compliance with RFC 8259 syntax rules (double-quoted keys, valid escapes, and no trailing commas).
  • Alphabetical Key Sorting: Recursively orders object keys A–Z so you can compare two API responses cleanly in diff tools.

Common JSON syntax mistakes

  • Single quotes: Standard JSON strictly requires double quotes ("key": "value") for all strings and property names.
  • Trailing commas: Placing a comma after the last item in an array ([1, 2,]) or object causes strict JSON parsers to fail.
  • Unquoted keys: Every JSON object key must be enclosed in double quotes.
  • Leading zeros or comments: Numeric literals like 0123 and // comments are invalid in RFC 8259 JSON.

Frequently asked questions

Is my JSON data secure when using this formatter?

Yes. All parsing, validation, key sorting, formatting, and compression run exclusively inside your browser's local JavaScript runtime. Your data is never transmitted to any external server.

What does the JSON minifier do?

Minification strips all unnecessary spaces, tabs, and line breaks outside string literals, creating a compact single-line string that minimizes payload size.

Can I upload a .json file directly?

Yes. Click "Upload File" to read any local .json or .txt file directly into the input workspace.

What causes an "Unexpected token" syntax error in JSON?

This occurs when the parser encounters a character that violates RFC 8259, such as an unquoted property, a trailing comma, single quotation marks, or an unmatched brace or bracket.

How are Object Keys counted in the statistics panel?

The Object Keys counter totals every named property across root and nested JSON objects (including objects inside arrays) without counting numeric array indices as keys.

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