Knowledge Base
Shopping Cart Software Online Manual
Payment Gateway
Password Fields (Place an Order tool) Plesk
Location Home > Glossary

Payment Gateway

A payment gateway is a company that performs the validation of an online credit card purchase, and then makes the decision of whether to approve or decline the credit card transaction. The payment gateway is the system that transfers the funds from the customer's credit card into the merchant's bank account.
How does a payment gateway work?

A typical credit card transaction in an online store may go something like this:
  1. The customer visits the merchant's online store.
  2. The customer uses the merchant's shopping cart software (such as Modular Merchant) to add products to their cart and checkout.
  3. On the shopping cart's secure checkout page, the customer enters their credit card information and clicks a submit button.
  4. When the submit button is clicked, the shopping cart software makes an encrypted connection to the payment gateway, and then securely submits the credit card information to it.
  5. The payment gateway evaluates the credit card information and decides whether to approve or decline the transaction.
  6. If the payment gateway approves the transaction, it then debits the credit card and transfers the funds to the merchant's bank account.
  7. The payment gateway then sends its approval or decline message back to the shopping cart software.
  8. The shopping cart evaluates the response from the payment gateway, and takes the appropriate action, such as sending the customer a receipt for their order.

Steps four through eight above typically take, at most, just a few seconds.

When is a payment gateway required?

In order to validate and debit credit cards in real time, a shopping cart must be able to connect to a payment gateway. This is usually as simple as entering your payment gateway account information into your shopping cart's System Settings.

There are many payment gateways. Examples of just some of them include:

  • PayPal Website Payments Pro
  • PayFlow Pro
  • BluePay
  • LinkPoint
Typically, the shopping cart software's communication with a payment gateway happens nearly instantly, behind-the-scenes and doesn't require the customer to leave your website in order to complete the transaction.

There are also off-site payment gateways, which require the customer to leave your website and complete the transaction on the gateway's website.

An example of an off-site payment gateway would be:

  • PayPal Website Payments Standard

For more general information about Payment Gateways, see the Wikipedia article.

— Last Edited - 01/14/2014 10:04am PST
Comments: This article has 2 user comments.
  HH100Store said... April 04, 2012 -- 2:08pm PDT
Can I use Web Connect as my payment gateway? THis is with Heartland Payment Systems.
  cmarier said... April 04, 2012 -- 4:11pm PDT
I reviewed the list of payment gateways supported in MMv4, and the list currently includes:, Google Checkout, Manual (offline processing), PayPal Website Payments Pro (credit card gateway), PayPal Website Payments Standard (PayPal button) and SecurePay.

Additional payment gateways are evaluated on a case-by-case basis. If you have a payment gateway that you'd like to have considered, I would recommend starting a Support Ticket within your store's Administration Area and providing as many details about the payment gateway as possible, including: copies of, or links to, the gateway's integration/developer documentation and information about any "test account" area the gateway makes available for use while developing support for the gateway.
Rank and add a comment to this article
Only logged in users may leave comments and rank articles. Log in to have your say!
  Knowledge Base Home

  QuickCode™ Tag Glossary

  Modular Homepage

Not Logged in.
Either Log in or create a User Account.

Other articles in this category...



Admin Account

Administration Area


Alternate Storefront URL (Product Editor Field)


Attributes vs. Fields

Audio Samples (Product Editor Option)



Back Office



Billing Address

Bounce Date

Breadcrumb Links



Checkout Area


Control Panel

Core Shopping Cart Files


Credit Card Security Code

Cron Job



Customer Account

Customer Account Area

Customer Attribute

Customer Field

Customer Group


Digital Delivery

Digital Object

Digital Product

Display Order



Email Batch

Email Instance

Email Opt In

Email Queue

Email Series

Email Series Step

Email Template

End Date


Event Engine


Featured Product


File Storage Area


FTP Active/Passive Modes


Fulfillment Report

Gift Certificate

Grand Total

Hidden Category

Hidden Product




Inventory Control (Product Editor Option)

Inventory Object

ISO Codes

Knowledge Base

Manual (Process Offline) payment gateway


Modular Mailer

Modular Mailer Email Messages


Navigation Menu


Off-Site Payment Gateway

On Hold (Subscriptions)

Order Item

Order Processor

Parent Product

Part Number (Product Editor field)

Password Fields (Place an Order tool)

Payment Gateway


Price (Product Editor Field)

Price Suffix

Processing Order

Processing Times

Product Groups vs. Fields

Product Price

Public Event

QuickCode Block Tags

QuickCode Tag

Ranking Criteria and Ranking Criteria Groups

Redeem Limit


Retain Balance


RGB Value

Sale Price (Product Editor Field)

Search Keywords (Product Editor Field)


SEO Friendly URL


Shelf Life

Shipping Address

Shipping Method

Ships Solo (Product Editor Field)

Shopping Cart


Store-Generated Email Messages



Subscription Item

Subscription Product

Subscription Queue


System Log

System Settings


Template Package


This product may only be shipped by the following methods (Product Editor Option)

Trial Period


Universal Template

UNIX timestamp


Wish List: Public Access Code

Zone Fee