Authorize.net is a Splynx add-on used to synchronize customers, invoices and payments with the Authorize.net payment gateway - https://www.authorize.net.
The add-on can be installed in two methods, via the CLI or via the Web UI of your Splynx server.
To install the Authorize.net add-on via CLI, the following commands can be used:
apt-get update
apt-get install splynx-authorizenet
To install it via the Web UI:
Navigate to Config -> Integrations -> Addons:
Locate or search for the "splynx-authorize.net" addon and click on the install button in the Actions column:
Click on the "OK, confirm" button to begin the installation process:
After the installation process has completed, you have to configure the add-on under Config / Integrations / Modules list, locate or search for the "Splynx AuthorizeNet Recurring Billing Add-On", and click on the edit 
icon the Actions column, as depicted in the images below:
API domain - your Splynx URL.
API key, API secret - default values. Don't change this if it is not completely necessary.
Payment account - select AuthorizeNet.
Payment method - when a customer pays using this add-on, the payment will be allocated as this payment type.
Transaction fee category - transaction category of the service fee. It is only used for proforma invoices. For invoices service fee category is always Service.
Service fee - service fee (in %).
Fee VAT - service fee VAT percent.
Fee message - service fee description.
Add fee to request - enable/disable adding fees to requests
Bank statements group - Group bank statements (Finance → Payment Statements → History) monthly or daily.
Language - language of the addon.
API login id, Transaction key - described on the following page - https://support.authorize.net/s/article/How-do-I-obtain-my-API-Login-ID-and-Transaction-Key
Thereafter, customers can pay their invoices and refill balances using the Authorize.net system. They will see a new button To Pay in the customer portal, as depicted below:
To refill customers balances, the following link can be used - http://yoursplynxurl/authorizenet, where they will have to enter registration details for the first time:
On the dashboard of the portal, customers will also see the list of un-paid invoices and a "Pay" button near each invoice:
