Data tool

API Response Corruptor

Generate bad API responses on purpose so you can test frontend error handling, schema validation, retry logic, importers, and edge cases.

Runs Locally

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

API response input

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

Open file

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

Size

680 B

Lines

Keys

Objects

Arrays

Corrupted response

490 B output · valid JSON

Damage presetResponse shapeSeed

Validation status

Output can still be parsed as JSON, but its values/schema may be intentionally wrong.

{
  "status": 400,
  "requestId": "req_9f43a8c2",
  "data": {
    "user": {
      "id": null,
      "name": "Laramie Williamson",
      "email": "laramie@exaple.com",
      "role": null,
      "active": true,
      "createdAt": "2026-06-20T15:30:00Z"
    },
    "subscriptions": [
      null,
      {
        "id": "sub_002",
        "plan": "storagestoragestoragestorage",
        "currency": "USD",
        "renewing": null
      }
    ]
  },
  "meta": {
    "page": null
  },
  "ok": 0
}

API damage controls

Tune the exact failure modes you want your app to survive.

Fields removed14%Fields nulled16%Types swapped18%Keys renamed12%Collections emptied10%Array items duplicated12%Arrays reordered30%Strings mutated16%Extreme numbers12%Status/errors changed25%Latency/retry fields18%Syntax breakage6%

What this tool does

API Response Corruptor produces malformed versions of API responses, with missing fields, wrong types, truncated payloads, and broken structure, so you can see how your frontend and backend behave when an API misbehaves. It is the way to test the unhappy paths that are hard to trigger on purpose.

How it works

Paste a sample response, choose how to break it, and the tool generates corrupted versions in your browser. Copy them into your tests or mocks. Nothing is uploaded.

When to use API Response Corruptor

Testing how a frontend handles a broken response

Hardening error handling on the backend

Building mocks for failure scenarios

Checking retries and fallbacks against bad payloads

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