How to set up a card payment gateway in an online store

Raúl Carrión

Written by Raúl Carrión

How to set up a payment gatewayWhen setting up an online store, one of the steps that most concerns first-time entrepreneurs is how to set up a credit card payment gateway. Some even discard this payment method due to the complexity they see in its installation, opting instead to receive payments exclusively through PayPal.
From my point of view this decision is not wise because PayPal forces all buyers who do not have a PayPal account to re-enter all their contact details. This generates extra work for our buyers and a decrease in the degree of confidence in the transaction, thus increasing the number of baskets abandoned in the “awaiting payment” status.
With this article we will lose a little fear to the hiring and configuration of payment gateways with card, seeing what are the steps we have to take to hire the service and to configure it in our online store.

How to contract a credit card payment gateway?

Banks and savings banks are responsible for providing the Virtual POS service, also called “card payment gateway”. The quality of service is very similar in all of them as they usually share the same platform called Redsys. Depending on the entity chosen, the main change will be the economic conditions.


How much does a payment gateway cost?

Virtual POS fees usually include three separate line items:

  • Set-up or installation fee: it can reach up to 100€ and in our experience it is one of the easiest items to negotiate.
  • Fixed monthly fee: with a sufficient volume of sales it is usually reduced to 0€.
  • Percentage of turnover: also negotiable when sales increase. It is usually less than 1%.

The amount will depend on two factors:

  • Our degree of linkage with the entity: additional services contracted, such as insurance, payroll, investment plans, minimum amount to be deposited in the account, etc.
  • Our turnover: the amount we invoice in the online store through the virtual POS.

In principle, the higher these two values are, the more we will be able to reduce the commissions to be applied to our online store. However, I recommend that you request in writing all the current conditions and how the commissions will vary according to the volume of business generated to avoid surprises.

Taking into account the factors that influence the commissions for a card payment gateway, the most common is to contract the virtual POS in the bank where we already have other contracted services.

How to install a card payment gateway?

Once the conditions of the payment gateway have been negotiated (you always have to negotiate with banks) and accepted, the selected bank will send us an email with the necessary information to configure the virtual POS. Next we will see the steps to be performed:

Step 1- Log in to the POS panel and change the password

For security reasons, banks invite us to access the web panel of our POS to change the access password. The email we receive will detail in which section of our private area we must access to make this change.

Step 2 – Insert payment gateway data in the administration area of the online store

If it is an open source CMS such as Prestashop or Magento we must install a virtual POS module. Redsys offers modules for most of these content management systems for online stores.
If you use a custom web development or an e-commerce platform for rent, the module to insert the virtual POS data will come as standard in the platform itself.
The data to be inserted in the POS module are the following:

  • Name of the store: it is usually the name of the store in capital letters.
  • Trade number: a numerical code that uniquely identifies the trade to facilitate the bank’s management.
  • Terminal number: a counter in case the store has several terminals, by default it will be 001.
  • Terminal currency: the code that identifies the currency in which we will operate. In some modules it is not necessary to enter this data.
  • Secret encryption key: key that will encrypt the communication between the POS and the web.
  • Key type: the encryption method, in some modules it is not necessary to enter it.

All these data will be sent to us in the configuration email.

Step 3 – Perform pre-production tests

In this step we will have to make two tests: one test with an authorized purchase and another test with a denied purchase. In the documentation we will find the card number, card expiration date and security codes that we have to use for each of the two tests. Therefore, it is no more than simulating two purchases with the card data provided.

These tests will be recorded in our web panel, so it is advisable to log in to check that they have been carried out correctly.

Our last task in this step will be to send an email to our bank indicating that we have performed the tests correctly and also indicating our interest in moving the virtual POS to production.

The support team must also make a test purchase, to facilitate this operation we will send you in the email a user and password of a test client so that you can make a test order.

Step 4 – Transfer of the POS to production

If everything worked correctly we will receive an email with the new encryption key for the real environment and the call URL for the production environment. In many modules this URL does not have to be entered and there is simply a checkbutton that indicates whether the payment gateway is in pre-production or real mode.

To finalize the process once these data are updated we will make a purchase with a real card that is authorized and a purchase that is denied.

From that moment on, our credit card payment gateway will be operational to receive income. The only thing left to do is to add the credit card icons in the footer to indicate that this payment method is available in our online store.


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Raúl Carrión
Raúl Carrión
Former Product Manager of OptimizedStores - eCommerce at Human Level. Graduated in Computer Engineering. Subsequently, he completed a Master's Degree in Application Development and Web Services and a Master's Degree in Sales and Marketing Management. Specialist in web development and e-commerce, having worked with several CMS. Regular lecturer in national and international business schools.

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