• Open Banking APIs:  faster, cheaper, and more secure payments, alongside richer data and better customer experiences. 
• Build your own API solutions: for maximum control, customisation, and if it's a core competency, but be prepared for high investment and ongoing maintenance. 
• Buy solutions from providers: for speed, reduced complexity, cost predictability, and access to expert knowledge, allowing you to focus on your core business. 
• The strategic choice to build or buy: depends on your core competencies, resources, time to market, and total cost of ownership. 
• NatWest supports both: build (via APIs) or buy (via ready-made solutions like Payit), we’re here to help. 

Open Banking is driving big changes in the world of payments. For corporate decision-makers, this presents both an imperative and a significant opportunity. Open Banking application programming interfaces, or APIs, enable seamless, secure communication between financial institutions and third-party providers. This allows for innovative payment solutions, richer data insights, and improved customer experiences.  

The strategic question for many businesses is no longer if they should engage with Open Banking, but how. Specifically: should you build these capabilities in-house, or leverage existing solutions from expert providers? 

Understanding this build-or-buy dilemma is crucial for unlocking the full potential of Open Banking. Done right, it could lead to substantial cost savings, enhanced operational efficiency, and new revenue streams. Let’s explore the factors influencing this strategic choice, supported by relevant data and a practical framework for senior corporate leaders. 

Open Banking APIs are fundamentally reshaping how businesses manage payments and financial data. They allow for direct bank-to-bank payments, bypassing traditional card networks, and enable secure access to account information with customer consent. The benefits are compelling: 

1. Faster payments: direct bank transfers often settle in near real time, significantly improving cash flow and working capital. 
2. Reduced costs: by circumventing card scheme fees and interchange, businesses can realise substantial savings on transaction costs. Our models suggest that on 100,000 transactions at an average £80 basket, the annual saving could be around £880,000 when comparing account-to-account payments to traditional card costs. 
3. Enhanced security and fraud reduction: strong customer authentication (SCA) is inherent in Open Banking payments, and tools like confirmation of payee reduce misdirected payments and social engineering fraud. This can lead to a significant drop in chargebacks, eliminating associated fees and back-office handling. 
4. Richer data insights: APIs provide access to granular transaction data, which can be integrated into ERP and treasury management systems for more accurate reconciliation, better forecasting, and deeper financial analysis. 
5. Improved customer experience: streamlined payment journeys, often involving biometric authentication and pre-filled details, can boost conversion rates at checkout. 

The growth of Open Banking in the UK highlights its impact: the volume of Open Banking-based payments reached 351 million in 2025, a 57% rise on the previous year, according to the FCA.  

For some organisations, developing open banking API integrations in-house is the preferred route. This approach offers significant control and customisation, allowing businesses to tailor solutions precisely to their unique operational needs and customer journeys. 

Benefits of developing in-house:

• Control and customisation: building from scratch provides the freedom to design bespoke integrations that align perfectly with your existing IT architecture and business processes. This is especially valuable if your business has highly specific requirements or complex workflows that off-the-shelf solutions cannot fully address. 
• Core competency: if payments, fintech, or data analytics are central to your business model and a key differentiator, then investing in internal development can strengthen your competitive advantage. Companies with a strong in-house technical team and a strategic vision for proprietary financial technology might choose to build to develop unique offerings. 
• Long-term cost efficiency: while initial development costs can be significant, building in-house can potentially lead to lower recurring operational costs over time, as you avoid ongoing licensing fees or per-transaction charges from third-party providers. However, this must be weighed against the continuous investment required for maintenance, updates, and staying abreast of regulatory changes. 
• Fast issue identification and resolution: if outsourced, and depending on the level of support available from third-party providers, a lack visibility of the end-to-end journey could impact the time to identify and resolve bugs or issues. 

Key considerations for building: 

1. Significant upfront investment: this includes hiring specialist developers, setting up infrastructure, and managing the development lifecycle. This is often a multi-year project. 
2. Ongoing maintenance and evolution: open banking standards and regulations are constantly evolving. An in-house team must dedicate resources to keeping integrations compliant and up to date. 
3. Regulatory burden: navigating complex payment regulations and data protection laws requires specialised legal and compliance expertise. 
4. Security implications: building secure API connections and protecting sensitive financial data demands robust cybersecurity measures and continuous vigilance. 

For many corporates, partnering with a specialist provider to "buy" open banking API solutions makes more strategic and economic sense. This approach allows businesses to rapidly deploy new capabilities, reduce operational complexity, and focus on their core activities. 

The value of adopting external solutions

• Speed to market: external solutions, often delivered as a service, enable much faster implementation. This is critical in a rapidly moving market where gaining an early advantage can be decisive. 
• Reduced complexity: integrating with open banking APIs can be intricate. Buying a solution means offloading the technical complexities of API connections, data normalisation, and ongoing maintenance to an expert provider. 
• Cost efficiency and predictability: while there are recurring fees, these are often more predictable and can represent a lower total cost of ownership compared to the significant upfront and ongoing investments of an in-house build, especially for businesses where payments are not a core competency. 
• Expert knowledge and compliance: specialist providers are dedicated to staying current with all regulatory developments, security protocols, and evolving API standards. This can help ensure your integrations remain compliant and secure without requiring extensive internal resources. 
• Focus on core business: by outsourcing the Open Banking infrastructure, businesses can allocate their resources and talent towards their primary value-generating activities, improving overall productivity and innovation. Third-party providers may be better equipped to handle complaints or deal with issues in an efficient way. 
   

Key considerations for buying: 

1. Vendor reliance: you may risk becoming dependent on your chosen provider for functionality, updates, and support. Careful vendor selection and robust service level agreements (SLAs) are crucial. 
2. Less customisation: off-the-shelf solutions may offer less flexibility than a custom build. It is important to ensure the chosen solution meets a significant percentage of your requirements. 
3. Data ownership and privacy: understand how your data is handled, stored, and protected by the third-party provider, ensuring it aligns with your internal policies and regulations. 

The build-or-buy decision is not one-size-fits-all. It requires a thoughtful assessment of your specific business context: 

1. Assess core competencies: is building payment technology a core differentiator for your business, or is it a supporting function? If it’s the latter, buying is likely more efficient. 
2. Evaluate resources: honestly assess your internal budget, technical talent, and bandwidth. Do you have the sustained capacity for both initial development and long-term maintenance? 
3. Consider time to market: how quickly do you need to implement open banking capabilities to seize market opportunities or address competitive pressures? 
4. Weigh total cost of ownership (TCO): look beyond initial costs. Factor in ongoing maintenance, compliance, security, and the opportunity cost of diverting internal resources from other strategic projects. 
5. Future-proofing: consider how easily the chosen solution can adapt to future changes in open banking standards, new payment rails, and evolving business needs. 

At NatWest, we recognise the immense potential of Open Banking for businesses large and small. We offer a range of solutions and expertise to support businesses, whether they choose to build or buy. 

For those looking to build, our comprehensive suite of APIs, available through channels like Bankline Direct, provides the foundational components for deep integration. These APIs offer direct access to account information and payment initiation services, allowing your developers to craft custom solutions that fit your unique requirements. We provide the technical documentation, sandboxes, and expert support to facilitate your in-house development. 

For businesses that prefer to buy, NatWest offers ready-made solutions like Payit, our Open Banking payment gateway. Payit allows you to quickly integrate account-to-account payments into your checkout flows, delivering immediate benefits in terms of cost reduction, fraud prevention, and improved customer experience, all while NatWest manages the underlying API complexities and regulatory compliance. We also provide insights and support through our payments specialists, who can guide you in making informed decisions about the best open banking strategy for your business.

Open Banking APIs represent a pivotal shift in corporate payments, promising greater efficiency, security, and innovation. The decision to build your own solutions or leverage those from trusted providers is a strategic one, dependent on your business's core competencies, resources, and time-to-market objectives. By carefully evaluating the build-or-buy case and partnering with experts like NatWest, you can confidently navigate this evolving landscape, transforming your payment journeys and securing a competitive edge in the digital economy.