Modernizing Digital Banking on Fiserv Premier Without Core Migration

The Client

Our client is a community bank with $4.2 billion in assets and 38 branches in three states. It has used Fiserv Premier for more than 10 years. The core processes about 2.1 million transactions a month across retail and commercial accounts, and the bank's contract has seven years remaining on its Fiserv contract.

Premier continued to provide a stable transaction-processing foundation, but the digital systems surrounding it were no longer keeping pace with customer expectations. The online banking portal was a decade old, and customers under 40 were moving to neobanks and fintech apps.

Going into their core conversion in the middle of the current contract created operational risk that the board was not prepared to take. The bank needed to upgrade its digital channels and its compliance activities but staying on Premier.

The Challenge

The existing portal could not support mobile check deposit, real-time balance updates, or digital account opening, and only 23% of customers were using digital banking, while 11% of customers under 40 left each year.

Compliance processes created another operational burden. A four-person team spent about three weeks each quarter manually extracting and preparing data for BSA/AML reporting, HMDA filings, CRA documentation, and other compliance activities. A recent examination had flagged late filings and inconsistent audit trails.

The bank also had limited flexibility to extend its existing environment without relying on Fiserv professional services. The bank was looking for a development team that could operate in the Fiserv environment, plug in with the provided API's and integration standards, and augment its digital suite without replacing Premier or changing its transaction logic.

The Solution

Our team began working in the Premier environment at the start of the engagement and designed the modernization architecture around its existing core. The work was completed in four overlapping phases over 14 months.

Technologies Implemented: Fiserv Premier APIs, a RESTful middleware layer in Node.js and .NET, React for the web portal, Swift and Kotlin for the iOS and Android apps, Python for the fraud models, and AWS for hosting and model training within the bank's VPC. Compliance work included banking regulation requirements of PCI-DSS, BSA/AML, HMDA, CRA, and SOX; KYC and identity validation are required for account opening.

The Process: Our developers segmented the modernization initiative into four parallel phases, allowing the bank to launch new features, while retaining Premier as its single source of record:

Phase 1: Middleware and API layer

Months 1 to 4

• Built a RESTful integration layer between Premier and the front-end systems being modernized without modifying core transaction logic
• Set up real-time feeds for balances, transaction history, and account status
• Replaced the batch files that slowed the old portal

Phase 2: Digital banking front end

Months 3 to 8

• Built a new web portal and native iOS and Android apps in the bank's own branding
• Added mobile check deposit with OCR validation
• Added digital account opening with automated KYC verification
• Connected peer-to-peer transfers and bill pay to the existing ACH and wire infrastructure
• Added biometric login with device binding
• Routed applicable transactions through the existing Premier environment

Phase 3: Compliance automation

Months 6 to 11

• Automated data extraction from Premier for compliance workflows
• Generated structured outputs for BSA/AML reporting, HMDA filings, CRA documentation, and SOX-related control and reporting processes
• Created an audit trail showing what data was extracted, when it was processed, and how it was transformed
• Reduced manual compilation so compliance staff could focus on review and sign-off

Phase 4: Real-time fraud monitoring

Months 9 to 14

• Trained a detection model on the bank's own Premier transaction history
• Flagged unusual patterns and built evidence packages for suspicious activity report (SAR) filings
• Generated supporting evidence packages for the compliance team's review and SAR preparation
• Deployed the fraud-monitoring workload within the bank's-controlled environment using AWS resources in its VPC

The Impact

Within six months of launch, digital banking adoption increased from 23% to 62% of customers. During the same period following modernization, annual churn among customers under 40 declined from 11% to 4.3%. The bank got there without migrating off Fiserv Premier, repositioning, or taking the core offline.

Customer Experience

Mobile check deposit, which the old portal could not support, reached more than 14,000 deposits a month by the third month. Balances and transaction history now update in real time from Premier instead of waiting on batch files, so the portal and app show what the core shows. Customers can access current account information through the new web and mobile banking experiences while Premier remains the underlying system of record.

Compliance and Fraud

Automated workflows replaced much of the manual data preparation previously performed by the compliance team. Data from Premier is processed into the required outputs for BSA/AML reporting, HMDA filings, CRA documentation, and relevant SOX control processes.

Compliance preparation decreased from approximately three weeks per quarter to a two-day review and sign-off cycle. Audit trails record the source, timing, and transformation of the underlying data, improving traceability in an area previously identified as a concern during examination.

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The fraud model gives the compliance team:

• Real-time alerts instead of next-day batch review
• Supporting evidence for flagged transactions to assist investigation and SAR preparation
• Fraud detection running within the bank's-controlled environment

Premier Remains the Core

Every new capability was integrated with the existing Premier environment without a core migration or changes to Premier's core transaction logic.

Transactions continue to post through Premier, allowing the bank to retain its established core environment and the operational continuity required by its board.

“We got a fintech-grade experience without touching the engine underneath." — Chief Technology Officer, community bank client

The middleware and API layer also gives the bank a reusable integration foundation for additional digital services. New front-end capabilities can connect through the same architecture while Premier remains the underlying system of record.