The power of one: How Citizens’ new open banking API framework came to life

Open banking is often painted as a consumer convenience, with banks spotlighting budgeting apps, personal finance tools, and consumer data portability as the core use cases. The real challenge for open banking lies in the commercial world, where companies need to integrate ERPs, accounting platforms, treasury systems, and multiple banking relationships – often turning what should be seamless connectivity into a costly, time-consuming puzzle. 

Commercial and corporate clients are often left to wrestle with clunky workarounds and weeks-long integrations. For CFOs, that can be the difference between a streamlined strategy and being buried in manual imports and reconciliation work.

That gap sparked Citizens’ launch of its open banking API redesign in mid-2024, which went on to take home Best New Embedded Finance Platform at Tearsheet’s The Big Bank Theory Awards 2025.

Here’s a closer look at how the Rhode Island–based bank reimagined its open banking API framework and what sets it apart.

The ‘rebuild’ mindset

Instead of chasing short-term fixes to its patchwork of legacy APIs, Citizens’ product and tech teams spent 2023 building something bigger: a framework that could stand up to the next decade of open banking demands. Clearing out screen scraping, reducing onboarding times, and eliminating fragmented integrations were all part of the mission – but the broader goal was even more ambitious.

The idea was to create one open banking API platform versatile enough to serve a range of clients while giving partners a unified, streamlined way to connect.

“The Citizens open banking experience supports all bank customers, including individuals, small businesses, and large corporations. By developing a unified API, we’ve sped up new feature rollouts and new platform connections,” said Michael Cummins, Head of Treasury and Payments Solutions at Citizens.

Engineering multiplexing: Closing the gap for businesses

What Citizens built is rare in US banking: a single open banking API that can flex to serve consumer, small business, private, and commercial banking clients alike.

The bank designed a unified interface based on Financial Data Exchange (FDX) standards. At its core is a ‘multiplexing’ system: the ability for the API to detect who the user is, what account type is being accessed, and what permissions are in place, then tailor the data output accordingly.

This means fintechs and ERP platforms don’t need five different integrations to work with Citizens. One connection adjusts itself to the client, whether it’s an individual linking a savings account or a corporate treasury team managing complex cash flows.

The results are already showing. Onboarding times dropped from weeks to minutes, and 96% of legacy screen scraping traffic vanished after rollout, according to the bank’s internal data. Having implemented this at scale, the Citizens open banking API processes millions of customer permissioned API calls per day. It shares key financial data that allows customers to manage their finances more seamlessly. This is a win on both the security and customer-experience fronts.

“By implementing a unified open banking API, we have accelerated the rollout of new features and simplified integration for new platforms, which in turn enables platforms to prioritize connecting with the Citizens API,” said Cummins.

The key differentiator

Citizens’ approach stood out because it addressed a blind spot. Research by Mastercard and Harris Poll showed that by late 2024, 85% of businesses were already using open banking services, and 92% saw them as essential to future-proofing their operations. Yet most bank APIs remained consumer-first, or consumer-only.

Citizens flipped the script by zeroing in on this specific area. The bank made sure its new API could support commercial clients from day one – a rare feat among US banks – and the first to achieve this through a single open banking API.

For small businesses, that means better cash flow visibility. For larger commercial clients, it means treasury operations that are less manual and more transparent. Popular platforms connected for data sharing include Sage, Expensify, Ramp, Carta, Appfolio, and Bill.com. 

“Thousands of business clients from the Citizens business banking, corporate, and private bank divisions are now accessing their Citizens data through the open banking API,” noted Cummins. “Data sharing occurs instantaneously, and the process is streamlined for clients, requiring no implementation procedures or paperwork.”

Designing forward

Citizens’ open banking API framework is designed to scale horizontally across product lines, serving all customer segments through a unified architecture.

The bank is broadening the API’s scope to incorporate additional commercial data, such as enriched transaction details, corporate loans, corporate cards, and account activity beyond standard deposit and money market accounts.

The unified design makes it possible to introduce new features quickly and consistently for all customer segments, reducing silos, accelerating innovation, and strengthening the foundation for embedded finance partnerships.

That’s the key takeaway here: a bank applying design thinking not only to the front end, but across its entire infrastructure stack as well.