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> For a complete documentation index, see https://docs.hellodata.ai/llms.txt.

# Property ID Changes and Redirects

HelloData maintains a consistent property identifier (`id`) for each building to allow users to retrieve full property details and history. However, in rare but important edge cases, these IDs can change.

> **Info**
>
> The `/property/search` endpoint is always free—feel free to use it when something looks off.

## When Do Property IDs Change?

We may update the property ID you receive in the following scenarios:

### 1. Property Merges

When two properties (say A and B) are merged into one new property C:

* Both A and B will redirect to C.
* Your old `id` will still work and return property C.

### 2. Property Splits

When a property is split into multiple distinct properties:

* The old ID (e.g. A) will redirect to one of the resulting new properties (e.g. B or C).
* We recommend re-checking the `address` or `building_name` if you're unsure.

### 3. Major Address or Identity Changes

If a property's ZIP code, city, or address is significantly updated:

* We may assign a new ID to the updated property.
* The old ID will redirect to the new one.

> **Warning**
>
> If your request to `/property/{id}` returns a 404, it may be due to one of these transitions. Use `/property/search` to find the updated ID.

---

## Tips for Developers

* **Use Search as Backup**: If an ID returns unexpected results, confirm via the `/property/search` endpoint using name or address.
* **Alias Matching**: The `building_name_alias` and `street_address_alias` fields can help confirm that you’re looking at the right property.
* **Cache Sensibly**: Property IDs are generally stable, but if you rely on them long term, consider periodic revalidation.

---

## Example

You originally fetched:

```http
GET /property/11111-11111-11111-11111
{
  "id": "22222-22222-22222-22222",
  "building_name": "Main Street Apartments",
  "building_name_alias": ["Main Apartments"],
  "street_address": "1234 New Ave"
}
```

This is expected behavior—you're still seeing the correct property under the latest data we have. We redirect to the new ID to ensure you always get the most up-to-date information.