> ## Documentation Index
> Fetch the complete documentation index at: https://developer.zilmoney.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> API key based authentication

All API requests to Zil Money must be made over HTTPS and authenticated using an API key. Pass the API key in the header, with the authentication type set to Bearer Token. You can obtain your API key from the [Developer Panel](https://sandbox.onlinecheckwriter.com/manage/developer/index). Keep this key secure and ensure it remains hidden from client-side exposure.

```json Example theme={null}
curl --location '/checks' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer <Api Key>' \
--header 'Accept: application/json' \
--data '{
    "checks" : [
        {
            "bankAccountId" :"yd6LeMYmdQeE8Dx",
            "payeeId"       :"Xw2lx48MdGMzWyD",
            "categoryId"    :null,
            "serialNumber"  :"1001",
            "issueDate"     :"2020-10-25",
            "amount"        :100,
            "memo"          :"First, Test check using API",
            "note"          :"",
            "accountNumber" :"458756",
            "invoiceNumber" :"2545",
            "noSign"        :0,
            "noAmount"      :0,
            "noDate"        :0,
            "noPayee"       :0,
            "voucherId"     :null,
            "customElements" :
                {
                    "element1":"first class tracking",
                    "element2": "test sender"
                }
        }

```