Payment Gateway Integration for E-commerce Websites

on Dec29
payment gateway integration
Written by
James Davis
Written by James Davis
Senior Technical Writer at United Thinkers
Author of the Paylosophy blog, a veteran writer, and a stock analyst with extensive knowledge and experience in the financial services industry that allows me to cover the latest payment industry news, developments, and insights. Read more
payment gateway integration
Reviewed by
Kathrine Pensatori
Product Specialist at United Thinkers
Product specialist with more than 10 years of experience in the Payment Processing Industry. I help payment facilitators and PSPs solve their various payment processing issues. Read more

A lot of purchases nowadays are made through e-commerce websites and their number is steadily increasing. In some of our previous articles we addressed particular aspects of payment processing, focusing on different industries and models (restaurant industry, online marketplaces like Uber and AirBnB, and others). Lately we started getting many questions like: “How to integrate the payment gateway into our own website?” So, we feel that it is time to dedicate a separate article to payment processing for e-commerce websites, paying particular attention to payment gateway integration related issues.

While in most cases people, who would like to integrate a payment gateway into their e-commerce website, focus mostly on the technical aspect of the problem, in fact, we need to consider other, non-technical aspects as well.
The issue of payment gateway integration becomes relevant in a situation when you are looking for a processing partner to integrate your website with. Particularly, it concerns the following business types:

  • an individual merchant, that wants to accept payments through the website
  • a software developer, who creates websites of various kinds and looks for a universal solution to offer to his\her customers
  • a software company, working on a platform for clients that will need to process payments (say, for groups of merchants), such as a POS-platform or an online marketplace

In all these cases the solution is approximately the same. Let us try to consider the technical and non-technical aspects of the problem separately.

Payment Gateway Integration for E-commerce Websites: Technical Aspect

From technical standpoint, in order to implement the integration, you need to define, which fundamental functionality you need. At least, you will need the basic payment card processing functions. In the case of websites, mostly card-not-present (CNP) transactions are involved. However, some software platforms may require countertop or mobile payment terminals for their clients. That is why terminal integration aspect might also be relevant.

Beside that, you will have to decide whether you need to store payment card numbers or not. Potentially, you can implement sale operations using a payment page without having to store card numbers. If you need recurring billing, then your payment page should return a token instead of an actual card number. Thus, you will have to store the tokens for handling future recurring payments. Consequently, your integration becomes more complex. Also you will, most probably, have to implement refund and void operations.

Every gateway has its own specification for implementation of each of the listed operations, so you need to choose the gateway, where the specification makes sense to you as more suitable and understandable.
When you perform the integration you have to realize the PCI consequences of your actions. For instance, if actual card numbers are involved in exchange of information with the API, then you will definitely face the PCI consequences. That is why you have to understand the concept of hosted payment pages and see, whether you need use them.

Moreover, those who need to process recurring payments, have to understand tokenization concept as well. Finally, those who need terminal integration will have to get acquainted with terminal specifications. If you want to read more on the subject, one of our previous articles on EMV terminal solution implementation should be helpful.

Payment Gateway Integration for E-commerce Websites: Business Aspect

From business standpoint (non-technical aspect, that is no less important), the problem looks as follows. When selecting a platform, you are also selecting a business partner. If you are a software development company (making websites or service platform), you have to realize that beside being able to offer payment processing services to your merchants for your services, you might also be able to participate in residual revenue generated from the transactions that they will process. I.e., if you integrate with payment gateway X and bring new customers (merchants) to the gateway, the company might share with you a certain part of payment processing fees, collected from these merchants.

So, when you need your payment gateway to support just the basic functions and you have to choose among several prospective integration partners, then it might be advisable to choose the one that will let you make some money on processing of transactions of your future merchants.

Those who are dealing with an online platform or service (not just individual website) to be used by multiple merchants of different kinds, should, definitely, familiarize themselves with payment facilitator concept. They should select the platform that, beside classical payment processing API, supports merchant onboarding API as well. Here is a white paper, from which you can learn more about payment facilitator concept.


Whatever type of entity you represent, if you want to integrate your e-commerce website with a payment gateway, you should carefully analyse the task from both technical and business standpoints. Only in this case you will successfully and smoothly implement payment processing into your website and maximize your benefit without making costly mistakes.

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