Website Payment Integration: Step-by-Step Setup, APIs & Best Platforms (2025)

In today’s digital world, online payment volumes are constantly on the rise. According to the Indian Ministry of Finance, the digital payment volume has increased in India from 4300 crores in 2021 to around 18,000 crores in 2025. 

This reflects a huge shift from offline payment methods such as cash and checks to online methods. For businesses wanting to grow and expand internationally, integrating an online payment processor into their website or app can help boost sales and revenue immensely.

This article aims to cover what website payment integration is, how it works, its benefits and challenges, as well as future trends. 

Website payment integration involves integrating a payment processor into your website to allow a smooth, secure, and convenient payment process.

Integrating a payment gateway improves conversion rates by ensuring fast and secure transactions, enhances user experience by providing easy and secure payment processes, and optimizes revenue by encouraging customers to complete purchases.

Challenges in website payment integration include developer complexity with API setup and coding expertise, security risks requiring data protection and compliance with standards like PCI DSS, and currency handling issues due to multi-currency fees affecting international sales.

Website payment integration is the process of incorporating a payment gateway into your website. It enables you to accept digital payments easily and securely, as well as allows customer payment information to be transferred between your website and the bank easily. 

Payment gateways help customers pay online businesses by acting as an intermediary service that processes and authorizes digital transactions. 

Website payment integration for online transactions has various steps requiring you to choose a payment gateway, set up a merchant ID, obtain API keys, conduct a sandbox, and finally go live. The steps are detailed below:

Step 1: 

Before choosing a payment gateway, you should consider what your business needs are. You need to take into account transaction fees, types of payments, security and compliance standards, as well as compatibility with your website. 

Step 2:

After deciding which payment gateway to choose, you might need to set up your merchant ID. A merchant ID for a website can be compared to the address for a home. It is a unique number that businesses use to allow payment processors to identify where to send the funds during a transaction. 

Step 3:

The third step is to get API keys. API stands for Application Programming Interface, and it can be used to connect the payment gateway with your website. It is a set of rules that allows the platform and gateway to communicate with each other in a secure way.

Step 4:

Now, it is time to integrate the payment gateway into your website. You can either code for payment integration in a website, embed a checkout.js/stripe.js JavaScript library, or you can use platforms such as Shopify and WooCommerce. These allow for straightforward integration through plugins and extensions. 

Step 5:

Before you let customers use the payment gateway, you should offer a sandbox mode. This allows you to make test purchases and check if everything is working smoothly without any bugs. 

Step 6:

You can finally go live and allow your customers to pay through the gateway.  

Website payment integration has various benefits relating to conversion rate, user experience, and revenue optimization. They are shown below: 

Conversion rate

By integrating a payment gateway into your website, you can ensure customers have a fast, secure, and smooth transaction, with no issues. This allows conversion rates to increase by reducing cart abandonments, speeding up payments, and improving customer satisfaction. 

User experience

Businesses can improve the user experience to make sure that customers visit their platform or website often. Integrating the payment processor directly into their platforms allows users to have a convenient, secure, and easily accessible payment process. They do not have to go to a separate payment portal, their sensitive information is not shared, and they can retrieve their purchase history information easily. This all goes a long way in improving the user experience.  

Revenue optimization

By working on making the payment process better for users, your business can increase the conversion rate, which leads to higher revenue or profits for the company. If the payment process is easy and secure, customers are more likely to complete that purchase. 

Website payment integration occurs across various industries such as e-commerce, SaaS, online      courses, marketplaces, and digital services: 

1. E-commerce 

Through website payment integration, e-commerce sites can accept fast, transparent, and secure payments. This improves customer trust and satisfaction. 

2. SaaS

Subscription as a service companies need to provide smooth billing for both one-time payments and subscription management. To create a smooth and seamless process for customers, businesses should integrate a payment processor into their website.

3. Online courses

Not only does having an integrated payment processor on the website help creators receive payments securely, but it also helps protect the students’ private information. 

4. Marketplace

Marketplaces have multiple vendors selling their own products, which is why having a secure payment processor is extremely important. It will help vendors process the transactions as well as issue refunds and chargebacks if needed. 

5. Digital Services

For any digital service, having an integrated payment processor creates a convenient and smooth payment process for customer transactions. 

The different methods a company can use to process payments are payment integration, Redirect-based checkout, and hosted payment pages. Payment integration allows the payment processor to be integrated into the business’s platform or website. Redirect-based checkout diverts the customer to an outsourced payment processor such as PayPal or Razorpay to pay, after which they are redirected back to the website. Hosted payment pages make customers leave the page to go to a payment processing app manually.

The differences between their process, advantages, and disadvantages are mentioned below:

There are different types of website payment integration methods, such as API-based, plugin-based, embedded checkout, and headless commerce. They are elaborated on below: 

1. API-based

API-based website payment integration allows e-commerce sites to interact with the payment processor or gateway to perform transactions. Through it, e-commerce merchants can manage their payments better. Webhooks are a big part of API based payment. It essentially communicates data via HTTPS between different application programming interfaces. Some examples of API-based integrations are UPI/cards/NetBanking.     

2. Plugin-based

Plugin-based integration refers to linking a pre-existing software that is used for payment processing to your website. It allows you to accept online payments directly from your platform, without having to redirect your customer or spending money to build your own processor. Some examples, such as Stripe, PayPal and Razorpay, are cost-effective methods for companies to accept payments.  

3. Embedded checkout

Through embedded checkout, businesses can link payment processors directly into the software. This allows users to complete transactions on the website directly without being interrupted. 

4. Headless commerce

Headless commerce separates the front-end (the users and customers) of a website from the back-end (operations of a business). This means that if a business wants to change something in the front-end to cater to growing customer needs, they can easily do so without affecting the operations of the website. This can give businesses flexibility to add more payment gateways or processors on their website, leading to customers having increased payment options. 

Website payment integration can suffer from various challenges, such as developer complexity, security risks, and currency handling.     

1. Developer complexity

Developer complexity arises from the fact that connecting a payment gateway with your currency systems by setting up APIs can be a task. Additionally, having to make sure that it works smoothly and fulfills customer needs is also important. Whether you are trying to integrate a basic or complex gateway, any API payment integration requires a level of coding expertise as well as a good understanding of the back end of your business. 

2. Security risks

Ensuring that customers’ sensitive information remains secure should be the priority for every business. Their personal data should be kept safe from fraud and cyberattacks. On top of that, a payment gateway integration system needs to follow the compliance and regulatory standards such as PCI DSS. Fraud detection tools (Radar and Fraud.net) also help in protecting businesses from fraud attempts. 

3. Currency handling

Not having multi-currency support can impact your business significantly. Most websites or payment processors tend to charge high fees for multi-currency transactions or cross-border payments, which can result in fewer sales internationally. 

Some best practices for website payment integration, such as PCI DSS compliance, sandbox testing, and mobile optimization, are mentioned below: 

1. PCI-DSS compliance

PCI DSS, or Payment Card Industry Data Security Standard, refers to the requirements businesses should follow if they are storing, processing, or transmitting payment account data anywhere. It helps reduce fraud by encrypting customer information, regularly testing the security, and applying strict access to only the cardholder. 

2. Sandbox testing

Sandbox testing or sandbox mode refers to payments made by businesses during the development or integration of the payment processor into the website. It is done as a test in a simulated environment, with information that might not be real. 

3. Mobile optimization

Most people make use of their mobile devices to conduct payments. Optimizing your payment processors to suit mobile transactions can increase customer satisfaction, which can lead to higher conversion rates.

Shopify and WooCommerce are e-commerce platforms that allow businesses to manage an online store. WooCommerce allows WordPress websites to be converted into stores, while Shopify lets businesses of all sizes sell their products online through their platform. Both of them provide businesses with the flexibility of choosing a third-party payment processor. Webflow can help businesses that have      low coding knowledge build websites for their products through a drag-and-drop design.

Any business that uses Shopify, WooCommerce, or Webflow to sell their products and create a storefront or website for their products should integrate Xflow into their custom stack. 

A custom stack for payments refers to the technological components and services a business makes use of to create a flexible and reliable payment system. 

Xflow helps businesses receive international payments quickly and safely with no hidden costs. It offers next-day payment settlements and shows live exchange rates, so businesses know exactly how much money they will get. Its virtual bank accounts allow clients to pay locally, reducing fees and speeding up payments. 

Xflow’s secure system is trusted by major banks, making it reliable for businesses of all sizes to handle global transactions easily.

Some regulatory and compliance standards to keep in mind for website payment integration are CVV/3D Secure, KYC, Data localization, ERP, and CRM tools.     

1. 3D Secure

3D Secure makes use of one-time password (OTP) or biometric authentication to ensure the verification of a purchase. It helps businesses prevent cyberattacks and add more security to their payment process. 

2. KYC 

KYC or Know Your Customer is a security check that allows financial institutions to verify a user's identity. During payment integration, it helps businesses assess risks and prevent money laundering and fraud. 

3. Data localization

Data localization refers to a practice where some countries require businesses to store and process data of their citizens in their home country. This is done due to security and privacy concerns, so for businesses wanting to expand in those countries, they have to keep in mind the data localization requirements. 

4. ERP/CRM tools 

Enterprise Resource Planning (ERP) integration removes the need for manual data entry, reduces errors, and automates the payment process, leading to a smoother transaction. Customer Relationship Management (CRM) systems automatically send customers their invoices and help keep track of the payment status. It can help businesses stay audit-ready. 

5. CVV verification

Card Verification Value, or CVV, is a three or four-digit number on the back of credit or debit cards that helps in verifying customer identity while making a purchase. 

1. Low-Code APIs

Low-code APIs do not require much coding expertise to create websites. This can give businesses a cost-effective method of creating and managing a website for their product.

2.  AI-based personalization

This refers to using AI for personalizing messages, product recommendations and services to customers based on their behavior. The AI can analyze and learn from its actions, creating personalized tools that would increase engagement, customer satisfaction, and conversion rates. This would lead to higher revenue and profit margins for your business. 

3. Real-time routing

Real-time routing is a mechanism that businesses can use to direct customers to the most suitable or cost-efficient route. This can allow for smoother and lower-cost transactions, increasing customer satisfaction and also the likelihood of successful payments. 

Xflow is the ideal partner for fast, secure, and scalable cross-border payment integration, empowering global businesses to grow effortlessly.

• Transparent flat 1% transaction fees with no hidden foreign exchange markups.
• Guaranteed live FX rates locked for predictability and accurate receivables.
• Settlement within one business day using local payment networks.
• Supports large invoice payments over $10,000 in a single transaction.
• Automated e-FIRA certificate issuance for easy regulatory compliance.
• Robust API for seamless integration with e-commerce platforms, custom stacks, and ERP/CRM tools.
• Secure transaction processing with built-in fraud detection and risk controls.
• Simplifies multi-currency handling for worldwide customer payments.
• Minimizes manual reconciliation and operational overhead.
• Flexible scalability to support startups through large enterprises.