QMerchant can help to process Payments in QuickBooks with Authorize.Net. Use this customized solution to process credit-card and electronic-check payments from QuickBooks via Authorize.Net, PayPal, and Others.
The payment requests are invoked directly from QuickBooks and transmitted to your payment provider.
Supports most QuickBooks versions including QuickBooks - Point of Sale (POS) and QuickBooks Enterprise.

Q-Merchant is a desktop application, which sits in between QuickBooks and the merchant processor. The following schema shows how it works:
1. Open QuickBooks first and then open Q-Merchant and connect to QuickBooks.
2. Create a transaction in QuickBooks, select the appropriate payment method and save.
3. Q-Merchant displays its payment dialog
4. Review the information and submit it to your chosen payment provider
5. Wait for the result. If the payment is accepted, the transaction id and other payment information are stored back into QuickBooks (depends on your settings and your QuickBooks version)
6. Close Q-Merchant payment dialog.

Requirements:
* .NET Framework
* QuickBooks 2004 Pro or higher
* QuickBooks Point of Sale
* A valid merchant payment provider account

Limitations:
* The software only accepts transactions in the payment processors test mode only. A trial key, available on request, unlocks all the functions for a short time.

The license of this software is Free Trial Software, the price is $275.00, you can free download and get a free trial.