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JSON Formatter & Validator

Validate, format, and minify JSON data with syntax highlighting and error detection.

Paste any JSON string — whether minified, broken, or deeply nested — and the tool instantly pretty-prints it with 2-space indentation, validates the syntax, and reports errors with exact line and column numbers. Toggle minified mode to remove whitespace for production payloads. Also shows statistics: total nodes, max depth, object key count, and root type.

Updated Enis GetmezFounder & Lead Engineer

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Quick answer

Paste any JSON string — whether minified, broken, or deeply nested — and the tool instantly pretty-prints it with 2-space indentation, validates the syntax, and reports errors with exact line and column numbers. Toggle minified mode to remove whitespace for production payloads. Also shows statistics: total nodes, max depth, object key count, and root type.

What is JSON Formatter & Validator?

The JSON Formatter and Validator is a free online tool that instantly pretty-prints, minifies, and validates JSON (JavaScript Object Notation) data. It conforms to RFC 8259 — the official JSON specification — and catches common mistakes like trailing commas, unquoted keys, and mismatched brackets. For valid input, it returns both a human-readable formatted version (2-space indent) and a production-ready minified version, along with structural statistics you can use to understand complex payloads at a glance.

How to use JSON Formatter & Validator

  1. 1

    Paste your raw JSON

    Drop any JSON string into the input — an API response, a config file, a Postman export, or the contents of a .json file. The tool accepts strings up to several megabytes.

  2. 2

    Get instant validation

    If the JSON is invalid, you'll see the exact line and column of the syntax error with a descriptive message ("Expected closing }", "Unterminated string", etc.).

  3. 3

    Copy the formatted version

    Valid JSON is auto-formatted with 2-space indentation and sorted keys (optional). Copy-paste it back into your codebase, documentation, or API docs.

  4. 4

    Minify for production

    For API payloads and embedded strings, toggle minified output — all whitespace is stripped, reducing bandwidth by 30-60% without changing meaning.

Try it when you need to…

  • Debug an API response that's returning a massive single-line JSON blob
  • Validate a package.json or tsconfig.json before committing changes
  • Track down a syntax error in a hand-edited configuration file
  • Minify a JSON payload before embedding it in an HTML data-attribute
  • Inspect deeply nested API responses without a code editor

Use cases

  • Debug API responses by formatting raw JSON
  • Validate JSON configuration files before deployment
  • Minify JSON payloads to reduce bandwidth
  • Inspect complex nested JSON structures
  • Learn JSON syntax with instant error feedback

Key features

Syntax validation with precise error location (line + column)
Pretty-print with 2-space indentation
Minified output for production use
Statistics: type, node count, depth, key count
Handles strings up to several megabytes
Unicode-safe — preserves emoji, Turkish, Arabic, and CJK characters

Tips & best practices

Trailing commas and comments are NOT valid JSON. If you're writing config files that need those, use JSON5 or JSONC instead.

For large API responses, the depth and node-count stats tell you at a glance whether you're dealing with a simple flat object or a multi-level nested mess.

Never paste tokens, passwords, or credentials into any online JSON tool. For secrets, use a local editor like VS Code with the "JSON" view mode.

Frequently asked questions

Standard JSON (RFC 8259) — objects, arrays, strings, numbers, booleans, and null. Trailing commas and comments are not valid JSON and will be flagged as syntax errors. For comment-support, use JSON5 or JSONC in a local tool.

The tool handles JSON up to several megabytes. Very large files (>5 MB) may take a moment to process. For multi-gigabyte datasets, use streaming tools like jq on the command line.

Yes by default. If you want alphabetically-sorted keys (useful for diffing two JSON files), use a CLI tool like jq --sort-keys.

Not directly — those aren't valid JSON. Strip the comments first, or use JSON5 instead (it supports comments and trailing commas).

No. Every request is processed on the fly and not retained in our database or logs. Still, avoid pasting JSON containing production secrets into any online tool, ours or otherwise.

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