Many different kinds of companies can benefit from an open source payment gateway, but three types of companies can particularly benefit. Open source products are common in many industries, and it makes sense that commercial open source software would come to the payment processing industry.
Those three types of companies that can most benefit from a robust, modern and completely flexible payment gateway are:
Payment facilitators. Since payment facilitators process lots of transactions, having the best possible system makes real sense. A properly designed gateway is robust and universal and can be the intermediary for connection with other gateways and make a single point of record. Direct connections with acquirers are also available for even more convenience, allowing the gateway to replace old systems.
Legacy system users. Many companies function on software written decades ago in now-obsolete languages. A modern open source solution is the right choice for replacing obsolete mainframe programs.
Software companies. Some software companies have started working with payment gateways to offer their customers the most complete solution. If your company provides POS systems, shopping carts or something similar, why not provide gateway capabilities too?