What is the ruling on working in the field of software and application development for online electronic payment service providers (Ogone, Ingenico)?

Electronic payment gateways act as intermediaries between the seller and the buyer and charge a commission. The problems that may arise are: using credit cards with late payment penalties, and displaying forbidden goods. There is no consequence for the website regarding the first problem because the relationship is between the customer and the bank. As for the second problem, the basic ruling for these websites is permissibility, and the presence of forbidden goods does not forbid dealing with them or programming them; because the one who commits the forbidden act bears its sin, and it is similar to building a marketplace where forbidden items might be sold, but the origin and the غالب (prevailing) is permissibility, unless the programming directly aids in the forbidden, such as placing links to forbidden items.