Step 11. Assign the product to another source [Web API Tutorial]

Endpoint
POST http://<host>/rest/all/V1/inventory/source-items

HTTP headers
Content-Type application/json
Authorization: Bearer <admin_token>

Payload

{
  "sourceItems": [
    {
      "sku": "Simple Running Backpack",
      "source_code": "txspeqs",
      "quantity": 250,
      "status": 1
    }
  ]
}

Response
Magento returns an empty array.
[]

Complete cURL request sample

source_code_1="default" && curl -X POST "$endpoint/all/V1/inventory/source-items" \
 -H "Content-Type: application/json" \
 -H "Authorization: Bearer $admin_token" \
 -d '{"sourceItems":[{"sku":"'"$productSKU"'","source_code":"'"$source_code_2"'","quantity":250,"status":1}]}'