JSON Formatter

Data Formatting

Format, validate, and minify JSON with line/column syntax error detection.

Indent:

Raw JSON Input

Formatted Output

Technical Specification & Client Security

Format, validate, and minify JSON with line/column syntax error detection. All formatting, transformations, and diffing algorithms run directly in your browser using local Web Workers and client RAM. No source code, authentication tokens, or database queries are sent across the network.

›Exact line & column error diagnostics for malformed JSON syntax

›One-click auto-repair for trailing commas, unquoted keys, and single quotes

›Web Worker off-thread processing for massive 10MB+ JSON payloads

›Adjustable indentation levels: 2 spaces, 4 spaces, or hard tabs

›Instant file export (.json) and direct file upload without server transit

›Automatic local storage persistence to prevent accidental data loss

Input & Output Transformation Examples

Minified to Pretty-Printed (2 spaces)

Input:

{"service":"auth","status":"healthy","uptime_sec":86400}

Output:

{
  "service": "auth",
  "status": "healthy",
  "uptime_sec": 86400
}

Syntax Error Detection with Auto-Fix

Input:

{'name': 'admin', 'roles': ['read', 'write',],}

Output:

{
  "name": "admin",
  "roles": [
    "read",
    "write"
  ]
}

Frequently Asked Questions

Is it safe to paste confidential or production JSON here?

Yes. Every formatting and validation routine executes strictly in your browser's local JavaScript/Web Worker sandbox. No payload data, tokens, or strings are transmitted over the network or saved to any remote database.

How large of a JSON document can this tool format?

Because processing runs inside a dedicated background Web Worker, documents upwards of 10MB to 50MB parse smoothly without freezing the browser's UI thread or stalling typing responsiveness.

Can this tool fix common syntax mistakes automatically?

Yes. If you paste JavaScript object syntax with single quotes, unquoted keys, or trailing commas, click the 'Auto-fix' button in the diagnostic banner to convert it to valid RFC 8259 JSON instantly.

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