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Free Online JSON Formatter & Indenter (JSONC, JS Objects, JSONL)

The best free online JSON formatter and indenter. Format, validate, and pretty-print raw JSON, JSONC with comments, JS object literals, escaped logs, and JSON Lines. Private local browser execution.

100% Local Processing: Your data never leaves your browser.
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How to use

  1. Paste your text (standard JSON, JSON with comments, loose JS objects, escaped strings, or JSON Lines) into the input area.
  2. Select your preferred indentation spacing (2 spaces, 4 spaces, or tabs).
  3. The tool will clean, validate, and display the formatted JSON instantly.
  4. Copy the result to your clipboard or download it as a .json file.

About Free Online JSON Formatter & Indenter (JSONC, JS Objects, JSONL)

The Free Online JSON Formatter & Indenter is an advanced, ultra-tolerant utility designed for developers, integration engineers, and data analysts. Unlike standard strict formatters that fail on the slightest syntax issue, our smart preprocessor sanitizes and formats a wide variety of format variations.

Key features include:

* **JSON with Comments (JSONC):** Automatically strip single-line (//) and block (/* */) comments, perfect for formatting configuration files like tsconfig.json or VS Code settings.

* **Loose JS Object Literals:** Convert raw JavaScript/TypeScript objects to valid JSON by quoting unquoted object keys and converting single quotes to double quotes.

* **Trailing Commas Removal:** Clean up trailing commas at the end of objects and arrays, a common copy-paste artifact from modern JS codebases.

* **Escaped JSON String Unescaping:** Instantly parse and format stringified JSON payloads copied directly from server application logs (containing raw \" characters).

* **JSON Lines & Concatenated Objects:** Detect and merge multiple sequential JSON objects or JSONL files into a single, perfectly structured JSON array.

Everything runs completely inside your web browser using client-side JavaScript. None of your data, variables, credentials, or API logs are ever uploaded to a remote server, ensuring total data privacy.

Real-World Use Cases

Configuration Formatting

Format files with comments like tsconfig.json or system settings files seamlessly.

Loose Code Normalization

Convert JavaScript object declarations copied from source code directly into valid JSON arrays or objects.

Log Payloads Formatting

Unescape and pretty-print JSON payload string strings copied directly from application crash logs.

Best Practices & Tips

You can paste comments (//, /* */) or loose JS object keys. The tool will automatically handle the conversion to strict JSON specifications.

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Frequently Asked Questions

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