> For the complete documentation index, see [llms.txt](https://galmis.gitbook.io/serializer-product-tracking/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://galmis.gitbook.io/serializer-product-tracking/getting-started/sharing-and-integration/development-api-reference/app-proxy-rest-api.md).
# App Proxy REST API
The app provides a secure REST API to the internal items' data via Shopify's [app proxy](https://shopify.dev/apps/online-store/app-proxies) **/apps/serializer/items** endpoint using **HTTP GET** method.
The endpoint accepts the following API query filters:
| Filter name | Type | Description |
| -------------------- | ------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
| **orderId** | Integer | Shopify's numeric order ID. |
| **customerId** | Integer | Shopify's numeric customer ID. |
| **productVariantId** | Integer | Shopify's numeric product variant ID. |
| **lineItemId** | Integer | Shopify's numeric line item ID. |
| **serialNumber** | String | Manually entered serial number. |
| **itemId** | String | Globally unique item ID generated by the app. |
| **itemRef** | String | It filters results by serialNumber or itemId. The filter may be helpful when the store uses both serialNumber and itemId fields as serial numbers. |
| **cursor** | String | Results are limited to 100 items per request. The filter provides a capability to paginate through the results. |
{% hint style="info" %}
The API endpoint requires at least one of the following filters to be used: **orderId**, **customerId**, **serialNumber**, **itemId** or **itemRef**. For example, `GET /apps/serializer/items?orderId=4460047270069`.
{% endhint %}
The endpoint response contains the following JSON data:
| Field name | Type | Description |
| --------------- | -------------- | --------------------------------------------------------- |
| **previous** | String | Cursor to the previous page |
| **hasPrevious** | Boolean | It highlights whether the previous page exists |
| **next** | String | Cursor to the next page |
| **hasNext** | String | It highlights whether the next page exists |
| **results** | Array of items | See the table below for the information about item fields |
Item fields:
| Field name | Type | Description |
| -------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------- |
| **lineItemId** | Integer | Shopify's numeric line item ID |
| **productVariantId** | Integer | Shopify's numeric customer ID |
| **itemId** | String | Globally unique item ID generated by the app. It can be used as a serial number. |
| **serialNumber** | String or undefined (not populated) | Manually entered serial number |
| **warrantyDuration** | Undefined (not populated), null or JSON object containing the following fields:
- unit - string. Possible values are "day", "month" or "year".
- value - integer, the minimum value is 1.
| Warranty duration for the item |
| **customFields** | Undefined (not populated for the saved items before the "Custom fields" feature release) or an array of JSON objects containing the following fields:
- key - string. Max length - 30 characters.
- value - string. Max length - 200 characters.
| It contains a list of all custom field values and keys associated with the item |
| **orderId** | Integer | Shopify's numeric order ID |
| **createdAt** | UTC timestamp in ISO-8601 format, string representation | Date and time when the item was first saved in the app's database |
| **updatedAt** | UTC timestamp in ISO-8601 format, string representation | Date and time the item was last updated in the app's database |