# GET /api/v1/credit/scorecard-versions/{from_version_id}/diff/{to_version_id}

> Compare two scorecard versions

- **Tag:** credit
- **Operation ID:** `diff_scorecard_versions`

## Description

Criteria and manual checks added, removed or changed from the first version to the second, with before and after for each changed field, and whether grade bands or scoring differ. To see which businesses come out differently, run a backtest with `compare_version_id`.

## Authentication

Bearer token in `Authorization` header.
Required header: `x-business-id: <business uuid>`.

## Parameters

- `from_version_id` (path, string, required)
- `to_version_id` (path, string, required)

## Responses

### 200 — Successful Response

Schema: `SuccessEnvelope_ScorecardDiffResponse_`

- `success` (boolean)
- `message` (string)
- `code` (string)
- `data` (ScorecardDiffResponse)

### 401 — Unauthorized - Missing or expired token, an MCP OAuth token used against the REST API, or no access to this business

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 403 — Forbidden - Insufficient permissions

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 404 — Not Found - Resource does not exist

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 422 — Validation Error

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

## Code samples

### cURL

```bash
curl -X GET 'https://api.ondayzero.com/api/v1/credit/scorecard-versions/{from_version_id}/diff/{to_version_id}' \
  -H 'Authorization: Bearer dz_your_token' \
  -H 'x-business-id: YOUR_BUSINESS_ID'
```

### JavaScript

```javascript
const response = await fetch('https://api.ondayzero.com/api/v1/credit/scorecard-versions/{from_version_id}/diff/{to_version_id}', {
  method: 'GET',
  headers: {
    Authorization: 'Bearer dz_your_token',
    'x-business-id': 'YOUR_BUSINESS_ID',
  },
});
const data = await response.json();
```

### Python

```python
import httpx

headers = {
    "Authorization": "Bearer dz_your_token",
    "x-business-id": "YOUR_BUSINESS_ID",
}

response = httpx.get("https://api.ondayzero.com/api/v1/credit/scorecard-versions/{from_version_id}/diff/{to_version_id}", headers=headers)
data = response.json()
```

## See also

- HTML version: https://www.ondayzero.com/docs/reference/credit/diff-scorecard-versions
- OpenAPI slice: https://www.ondayzero.com/docs/reference/credit/diff-scorecard-versions/openapi.json
- Other endpoints in **credit**: https://www.ondayzero.com/docs/reference/credit (markdown bundle: https://www.ondayzero.com/docs/reference/credit.md, OpenAPI: https://www.ondayzero.com/docs/reference/credit/openapi.json)
- Endpoint catalog: https://www.ondayzero.com/docs/reference/index.md