> ## Documentation Index
> Fetch the complete documentation index at: https://voucherify-pw-further-tests.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Update Customers' Metadata in Bulk

> Updates metadata parameters for a list of customers. Every resource in the list will receive the metadata defined in the request.

The request can include up to **10 MB** of data.

The response returns a unique asynchronous action ID. Use this ID in the query paramater of the [GET Async Action](ref:get-async-action) endpoint to check, e.g.:

- The status of your request (in queue, in progress, done, or failed)

- Resources that failed to be updated

- The report file with details about the update

If a product object is not found, it is **upserted**. This is shown in the report file in the **GET** Async Action endpoint. The upserted resources have value `false` in the `found` column and `true` in the `updated` column.

This API request starts a process that affects Voucherify data in bulk. In the case of small jobs (like bulk update), the request is put into a queue and processed when every other bulk request placed in the queue prior to this request is finished.