Data tool

JSON Corruptor

Break JSON on purpose to test validators, API clients, importers, error handling, and messy-data cleanup flows.

Runs Locally

This tool runs in your browser. Files never leave your device.

JSON input

Drop a JSON/TXT file here or paste JSON below.

Open file

Drag and drop a .json or .txt file anywhere inside this input card.

Lines

Objects

Arrays

Keys

Corrupted output

468 B output · invalid JSON

Damage presetSeed

Output validation

Expected property name or '}' in JSON at position 31 (line 5 column 1)

{
  "users": [
    null,
    {
// generated bad comment 584
      "iid": 1002,
      "iid_duplicate": 1002,
      "name": "Jane Doe",
// generated bad comment 966
      email: "jane@example.com",
      "plAn": "Free",
      "active": false,
      "credits": 18,
      "tags": [
        false,
        false
      ],
      "createdAt": "2026-06-03T11:15:00Z
    }
  ],
// generated bad comment 290
  "eta": {
    "page": 1,
    "hasMMore": false,
    "source": true,}
}

Damage controls

Use custom sliders when you need a specific kind of broken JSON.

Remove commas7%Add trailing commas10%Break quotes6%Unquote keys8%Mutate keys/values12%Blank values8%Duplicate keys7%Swap value types10%Insert comments8%Truncate output3%Insert junk text5%

What this tool does

JSON Corruptor creates intentionally damaged JSON data for testing applications, APIs, import systems, and validation workflows. Generate malformed JSON, missing fields, incorrect data types, and other realistic errors that developers encounter in production environments. Testing with corrupted JSON helps identify weaknesses before they become customer-facing issues.