About the Project
This project is a multi-bank marketplace built to solve a persistent problem in personal finance: finding and opening high-yield savings and CD accounts without friction, confusion, or hidden traps.
For most consumers, the process of hunting for better interest rates is tedious and unclear. Offers are scattered across different bank websites, terms are hard to compare, and application flows vary wildly from one institution to another. Many people end up staying with low-yield accounts simply because switching feels too complicated or risky.
The platform we helped build changes that by centralizing multiple partner banks into a single, consistent interface. Users can discover, compare, and open high-yield savings and CD accounts from trusted institutions, all in one place, without losing sight of fees, conditions, or risk. Under the hood, the platform integrates with multiple banks, keeps live interest rates up to date, and orchestrates a seamless onboarding experience via Single Sign-On (SSO).
The client’s vision extended across borders. Building on a strong track record in European fintech, they wanted two localized versions of the platform: one for the German market and another tailored to the U.S. market. Same core promise, different regulatory environments, user expectations, and partner ecosystems. Our role at Lumitech was to design and build a unified product foundation that could flex to both contexts without compromising either compliance or user experience.
Client Request
The client came to Lumitech with a proven track record. Having dominated segments of the German fintech space, they had a deep understanding of deposit brokerage logic. However, the U.S. market is drastically different. The client’s vision was to bridge the gap between "Big Tech" simplicity and "Big Bank" security.
Consumers in both the German and American markets faced similar frustrations:
The Onboarding Wall: Opening a high-yield savings account often required 20–30 minutes of manual data entry, physical document verification, and days of waiting for "trial deposits" to clear.
The Information Asymmetry: Interest rates change daily. Most savers are unaware when a better rate becomes available at a competing institution, leading to "lazy capital" that underperforms.
The Trust Deficit: In the wake of various financial crises, users are understandably wary of third-party platforms. Any friction in the UI is interpreted as a potential security risk.
The client’s mandate for the U.S. expansion was ambitious:
Multi-Bank Marketplace: A unified "shopping" experience for financial products where users could compare offers based on APY (Annual Percentage Yield), term lengths, and minimum deposits.
Universal SSO (Single Sign-On): A "one and done" onboarding experience. Once a user is verified, they should be able to open accounts at any partner bank without re-entering their data.
Live Real-Time Data: The platform needed to ingest and display live rate data from dozens of institutions simultaneously, ensuring the user always sees the most competitive offers.
Radical Transparency: A total removal of hidden maintenance fees or "teaser rates" that drop after a few months.
Personalized Financial Guidance: An AI-driven recommendation engine to help users optimize their "laddering" strategies for CDs and savings.
Our Approach
We structured the project around one core principle: one product brain, two market faces. That meant designing a product as a shared platform where logic, flows, and design foundations could be reused, while still leaving room for market-specific differences.
Market Localization: Beyond Language
Localization for the platform meant understanding the fundamental differences in how Americans and Germans save.
Regulatory Adaptation: In Germany, we deal with BaFin regulations; in the U.S., we had to account for FDIC insurance limits, KYC (Know Your Customer) standards under the Patriot Act, and AML (Anti-Money Laundering) protocols.
User Expectations: American users prioritize speed and mobile-first accessibility. We shifted the design language from the more formal, data-heavy German aesthetic to a cleaner, action-oriented U.S. interface.
Design & User Experience (UX) Psychology
We treated trust as a functional requirement. Our design team employed "Progressive Disclosure", a technique where complex financial information is broken down into digestible steps. This prevented "choice paralysis" when a user faced 20 different CD options.
The "Effortless" Feel: We utilized micro-interactions to provide instant feedback. When a user changes a filter, the yield calculations update in real-time with smooth transitions, reinforcing the feeling of a powerful, modern tool.
Technical Implementation & Architecture
The backbone of the project is a high-availability microservice architecture.
Data Pipeline: We built a proprietary data ingestion engine that polls partner APIs and scrapes authorized financial data points to ensure the "Live Rate" feature was accurate to the minute.
Identity Orchestration: The SSO capability was built using the OAuth 2.0 and OpenID Connect frameworks, wrapped in a custom layer that manages the secure transfer of PII (Personally Identifiable Information) between the platform and the partner bank cores.
Agile Launch & Iterative Evolution
We didn't believe in a "Big Bang" launch for a product involving people’s life savings. We utilized a "Soft Launch" strategy in selected U.S. states to test the SSO integration with a smaller subset of partner banks, allowing us to iron out edge cases in the KYC flow before scaling nationally.
Tools We Used
To support a multi-bank, multi-market platform, we chose a modern web stack that balances development speed with long-term maintainability.
On the frontend, we used:
React for a component-based UI, allowing us to build reusable patterns across both German and U.S. variants.
Next.js for routing, server-side rendering, and SEO-friendly pages—important for a consumer-facing financial product.
TypeScript to keep the codebase predictable and reduce runtime errors, especially around complex data structures like product definitions and rate tables.
On the backend and integration side, we:
Collaborated with the client’s team to expose secure APIs that aggregate rate and product data from partner banks.
Implemented robust data validation and normalization layers so that the UI always receives well-structured data, regardless of each bank’s internal format.
Architected SSO flows to ensure users could authenticate once and then seamlessly connect to partner institutions as needed.
For infrastructure, the platform runs on:
Cloud hosting (e.g., AWS) with scalable application services and managed databases.
Monitoring and logging to track rate update jobs, SSO success rates, and error patterns before they impact user experience.
A CI/CD pipeline so both the German and U.S. versions can be deployed quickly and safely, with confidence that shared code remains stable across both.
This foundation gives the client a platform that can integrate new banks, launch in additional regions, and add new product types without re-architecting the entire system.
Core Features
The final product was defined by five pillars of functionality that set it apart from traditional banking apps.
The Multi-Bank Savings & CD Marketplace
This is the heart of the project. We developed a sophisticated filtering system that allows users to sort by "Value over Time". Instead of just looking at the APY, users can see a projected earnings graph that compares a 12-month CD against a standard high-yield savings account, accounting for compounding interest.
Universal Single Sign-On (SSO)
Through our identity orchestration layer, a user undergoes identity verification (IDV) once. When they decide to open an account with a partner bank — say, "Bank A" — the platform securely passes the verified token to Bank A. The user never sees a second application form. This reduced the time-to-account-opening from days to under three minutes.
Live Rate Sync & Alert System
The platform doesn't just show rates; it monitors them. We implemented a "Rate Watch" feature that lets users set alerts. If a CD rate hits a certain threshold (e.g., 5.50% APY), the user receives a push notification, allowing them to capitalize on market shifts instantly.
The "No-Fee" Transparency Engine
Every financial product on the platform underwent a "Transparency Audit" by the compliance team. The UI was designed to highlight "The Fine Print" in plain English. If a CD had an early withdrawal penalty, it wasn't hidden in a PDF; it was displayed in a bold, clear callout box during the selection process.
Personalized Savings Recommendations
Using anonymized behavioral data, we built a recommendation engine. If the system detects a user has a large balance in a 0.01% checking account, it suggests a "Laddering Strategy" — splitting that capital across 3, 6, and 12-month CDs to maximize yield while maintaining liquidity.
Challenges
Designing and launching the project surfaced several key challenges (technical, regulatory, and experiential) that shaped the final product.
Multi-Institution SSO That Feels Seamless
Each partner bank had its own requirements around authentication, session handling, and security. Technically, that meant designing SSO flows that adhered to each bank’s standards while still feeling like a single, coherent journey from the user’s perspective. We had to carefully handle edge cases (expired sessions, partial applications, redirect loops) so users never felt “lost” or unsure whether they were still using the platform.
Real-Time Financial Data, Without Real-Time Chaos
Live rate updates were central to the value proposition. In practice, syncing data across multiple institutions with different update frequencies and reliability was non-trivial. We designed a high-availability data pipeline to fetch, validate, and update rates and terms, gracefully handling temporary failures or discrepancies. The UI was built to reflect the freshest available data without flickering or confusing the user with constant micro-changes.
Building Trust for a Marketplace Model
For many users, especially in newer markets, the idea of opening accounts through a marketplace rather than directly on a bank website is unfamiliar. The UX had to do a lot of trust-building: clear branding, visible partner banks, consistent disclosures, and explanations of how our client’s product fits into the picture. We paid particular attention to the wording of CTAs, disclosures, and helper text to avoid any sense of trickery or bait-and-switch.
Dual-Market Complexity Without Doubling Work
Supporting both German and U.S. markets introduced natural complexity: different regulations, naming conventions, and risk warnings. The challenge was to avoid creating two totally separate products that would be hard to maintain. Instead, we invested in a flexible design system and modular architecture so that most changes could be made once, then lightly adapted for each market.
Results
The launch of the U.S. platform yielded immediate, quantifiable success:
30% Faster Onboarding: By eliminating redundant forms through SSO, the average time to go from "Visitor" to "Account Holder" dropped by nearly a third.
20% Increase in User Engagement: The personalized recommendation engine led users checking the app 4 times more often than with their traditional banking apps.
Zero-Friction Conversion: Early beta testing showed that once a user opened their first account, the likelihood of them opening a second "Laddered" CD increased by 45%, proving the value of the centralized marketplace model.
Beyond the metrics, the client now has:
A dual-market platform that proves its model works in both its home (German/European) context and in the U.S.
A scalable technical and design foundation that can support new products, new banks, and future market expansions without starting from scratch.
A clear narrative for investors and partners: The product is redefining how savers discover and open high-yield savings and CDs, with a focus on speed, personalization, and transparency.
Summary
This project is more than just a savings app; it is a fundamental shift in the power dynamic between the bank and the saver. By centralizing the marketplace and removing the "switching cost" through SSO, we have empowered users to treat their savings as a dynamic, optimized portfolio rather than a static deposit.
At Lumitech, our role was to ensure that the technical complexity of cross-border banking remained invisible to the end user. We built a bridge between German financial engineering and American consumer agility.
Looking to build the next generation of fintech? Whether you are scaling a successful European model to the global stage or starting from scratch with a disruptive financial idea, Lumitech has the expertise in security, UX, and complex integrations to bring your vision to life.
