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How to integrate a payment gateway into a mobile app

Any company that wants to sell products or services through a mobile app will need a payment gateway. Payment gateways are responsible for securely transmitting sensitive cardholder data and are essential for facilitating online payments.  

Integrating a payment gateway into a mobile app can be straightforward or complex depending on how much manual, backend development is required. There are many modern, off-the-shelf payment gateways that seamlessly integrate into mobile apps and cater to the mobile user experience. However, for companies with complex or bespoke needs, integrating a payment gateway is more involved, requiring in-depth knowledge of app development, IT security, and compliance requirements.  

What is a payment gateway?

A payment gateway allows you to gather credit and debit card information from customers. It then securely transmits payment information for processing. Customers may easily pay for products and services with a credit or debit card thanks to gateway technology. Because clients engage with a gateway directly, it is commonly referred to as "front-end" software. 

Learn more about payment gateways: Setting up a payment gateway: A step-by-step guide

Adding a payment gateway to a mobile app: step by step 

Step 1: Research and choose a mobile payment gateway provider 

Before jumping into the process of integrating a payment gateway into your mobile app, research different providers to ensure the payment gateway will meet the needs of your company and your customers.  

Questions to ask potential gateway providers include:  

  • What security features are included in your gateway? 

  • How do you manage PCI DSS compliance? 

  • What is your fee structure, and are fees negotiable?  

  • How does your gateway cater to the mobile shopper?  

  • How can we customise the checkout screens to match our brand?  

  • Does your gateway allow for recurring payments? 

  • What card types and mobile wallets do you support?  

  • Do you offer localisation options for international payments? What currencies do you support? 

Step 2: Set up a merchant account for accepting payments 

A merchant account is necessary for accepting payments. It’s where the funds from each transaction are held temporarily until they’ve cleared and can be transferred to your business bank account.  

Many modern payment gateway providers also serve as merchant accounts, allowing you to manage both pre-transaction settings (e.g., payment methods, security features, recurring payment options) and post-transaction processes (e.g., chargebacks, refunds, fund transfers, etc.) all in one place. However, if you prefer to keep your merchant account separate, make sure that the payment gateway you choose integrates easily with that merchant account.  

Step 3: Configure payment methods and other gateway settings 

Once you’ve chosen a payment gateway provider and set up an account with them, log into that account to configure the settings and customise the user interface. This includes:  

  • Choosing which payment methods you’ll present to customers, such as card types (Visa, Mastercard, etc.) and mobile wallets (Apple Pay, Google Pay, etc.).  

  • Enabling and setting up the terms for subscriptions or recurring charges, if needed.   

  • Selecting which countries and currencies you would like the gateway to support.  

  • Updating the checkout page to include your company’s brand fonts, colours, and logo. 

Step 4: Obtain the gateway’s API and integrate it through code, SDKs, or widgets 

Once you’ve created your gateway account and configured the gateway settings, it’s time to add the gateway to your mobile app. This process varies depending on the payment gateway you’ve chosen, but many providers make it relatively easy for developers to add the gateway using their Application Programming Interface (API). Integrating the gateway’s API is what allows the app to access its payment processing infrastructure within the app, in real-time.  

Common ways of adding the payment gateway’s API include:  

  • Manual Coding - Developers can add the gateway’s API manually, with custom code they’ve written themselves.  

  • SDKs - Software Development Kits (SDKs) are sets of pre-written code libraries and tools that developers can use to add payment gateways to mobile apps with minimal manual coding required.  

  • Widgets - Some payment gateway providers offer payment widgets that developers can add to their mobile apps with a single line of code.  

Step 5:  Test and optimise the gateway  

The final step of adding a mobile app payment gateway is to test it in a non-live environment to make sure everything is working as it should. Most gateway providers allow merchants and their developers to run test payments to check for errors and make adjustments until the checkout process is seamless.  

After everything looks good and is working properly, it’s time to switch the gateway on and go live! Once live, monitor the payments closely from within your gateway and/or merchant account to further ensure transactions are processing correctly and as planned.  

Factors to consider when choosing a mobile payment gateway 

Security, compliance, and hosting 

When researching a payment gateway, it’s crucial to ensure it has security measures in place to protect your customers’ sensitive data. These security features may include encryption, tokenisation, multi-factor authentication, 3D Secure, and real-time fraud detection, among others.  

Your security and compliance requirements will vary depending on who is hosting the payment gateway. There are three main options for payment gateway hosting.  

  • API-hosted gateways (Recommended for most merchants)  
    With API-hosted payment gateways, customers remain in the app without being redirected during checkout. However, it’s the payment gateway provider—not the merchant—that manages their sensitive card data. 

  • Self-hosted gateways 
    A self-hosted payment gateway is one the merchant hosts directly on their app or website. This option requires extensive backend development and places all security and compliance responsibilities on the merchant.   

  • Hosted gateways 
    With hosted payment gateways, customers are redirected to the payment gateway provider’s website during checkout. This disruption in the user experience can distract and deter customers from following through with their purchase, particularly mobile app users who have come to expect a quick, seamless checkout process. 

Fees and fee structure 

When selecting a mobile payment gateway, it’s essential to understand the costs and fee structure involved, as these can vary significantly from provider to provider. Payment gateway providers typically charge merchants in one of the following ways: 

  • Fixed monthly fees 

  • Transaction fee 

  • Combination of fixed monthly fees and transaction fees 

Card transaction fees are usually structured as a percentage of the payment amount, plus a small, fixed cost. For example, a gateway may charge 2.9% + £0.20 for every transaction. Other costs to consider are any once-off setup fees, refund fees, withdrawal fees, chargeback fees, PCI compliance fees, and account termination fees.  

Depending on the size of the company and the volume of transactions, merchants may also be able to negotiate fees with their payment gateway provider. Many gateways may offer reduced fees as the volume of card payments increases.  

Currencies and service area 

If you’re planning on processing international payments through your app, it’s important to choose a payment gateway that caters to international customers.  

Check to make sure that the payment gateway will work in each country where you plan to do business. It can also be worthwhile to choose a payment gateway that automatically translates into the local language and allows customers to pay in their own currency.  

Available payment methods and types 

Not all payment gateways can process all card types and all mobile wallets. Consider which payment methods you would like to offer your customers and make sure your gateway is set up to support them. For example, which card types do you want to accept (e.g. Visa, Mastercard, Discover, etc.)? Do you want to allow customers to pay with mobile wallets, like Apple Pay or Google Pay?  

If you need to process recurring payments, such as subscription products or services, or recurring charitable donations, then you must also ensure your gateway can facilitate this.  

Branding and customisation 

Many payment gateway providers recognise the importance of customising the checkout experience to match each merchant’s specific brand. Choose a payment gateway that allows you to add your company’s logo and use your brand colours and fonts.  

Customising the look and feel of your mobile app payment gateway isn’t just about aesthetics. It also reassures customers that they’re in a familiar and secure environment, overseen by your trusted brand. It also helps seamlessly transition customers into the checkout process without any distractions or confusion. All of this serves to increase conversion rates and, subsequently, revenue for your business.  

Mobile user experience 

A seamless checkout experience is of the utmost importance when it comes to mobile shoppers, who are often “on the go” and unwilling to go through a multi-step payment process. 

When choosing a payment gateway for a mobile app, merchants can look for gateways designed specifically for mobile apps and mobile users. This ensures the gateway interface is responsive to the user’s device and that all aspects of the checkout process take place within the app. Mobile users are also more likely to prefer paying with a mobile wallet, such as Apple Pay or Google Pay, so it’s worthwhile to choose a payment gateway that allows mobile wallet payments.  

Customer Service 

In order to offer your customers the best possible service, it’s worth choosing a payment gateway that provides merchants excellent customer service as well. When researching a payment gateway, look into the type of support and availability they provide merchants and their IT teams.  

Consider choosing a provider that offers the following types of support: 

  • Knowledge centre with helpful guides and documents  

  • Community forum where developers can ask other developers questions about integrating and managing the gateway 

  • Multiple ways of contacting the support team, including: 

  • Phone support 

  • Email support 

  • Live web chat 

  • 24/7 availability for troubleshooting crucial issues in real-time 

Learn more: 10 tips to enhance your online payment experience

FAQs

How does a mobile app payment gateway differ from a standard payment gateway? 

A mobile app payment gateway serves the same purpose as a standard payment gateway—to securely transmit sensitive cardholder data during the payment process. The main difference between a traditional, online payment gateway and a mobile app payment gateway is that the latter is designed specifically with the mobile shopper in mind. It’s responsive to various mobile device screens and allows every step of the payment process to be completed within the app (rather than directing users out of the app to a separate website to complete the payment).   

Can payment gateways be customised to match the rest of the mobile app?   

Yes, many mobile payment gateway providers make it easy for companies to customise their checkout page to match their brand aesthetic. This includes adding the company’s logo, matching the brand colours, and using the brand fonts. Customising the look and feel of the payment gateway is an important part of creating a secure, seamless checkout experience for mobile customers.    

How much does a mobile payment gateway cost? 

Mobile payment gateway costs vary depending on the provider, the fee structure, and the volume of transactions processed each month. Many gateway providers charge merchants on a per-transaction basis, for example, 2.5% + 20p per transaction. Some providers also charge a fixed monthly fee.  

Many gateway providers also offer reduced fees as the volume of monthly transactions, or the amount of monthly or annual revenue, increases. It’s possible for merchants, particularly larger companies, to negotiate on costs and fee structures prior to signing an agreement with a payment gateway provider.  

What security features and compliance requirements should I consider when choosing a mobile payment gateway?  

When choosing a payment gateway, it’s crucial to understand how and where sensitive cardholder data will be transmitted and stored during the payment process. Unless your company has a legitimate reason for managing this data within its own servers, consider choosing a gateway provider that handles sensitive cardholder data on its own PCI DSS-validated servers.  

In addition to choosing a PCI DSS-compliant gateway provider, look for security features such as:  

  • SSL or TLS encryption 

  • Tokenisation  

  • 3D Secure 

  • Real-time fraud detection 

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