Case Study: Multi-Tenant BaaS (Banking-as-a-Service) Platform
A multi-tenant Banking-as-a-Service (BaaS) infrastructure built on AWS, enabling B2B clients to issue, activate, and process prepaid card transactions without managing native financial compliance layers.
The Problem
Deploying B2B card products typically requires navigating fragmented third-party protocols, slow identity verification, and rigid payment infrastructure that cannot adapt fee structures based on unique customer tiers or transaction types.
Engineering Features & Direct Impact
RESTful Middleware Wrapper: Encapsulates legacy third-party SOAP banking APIs into high-performance RESTful endpoints, simplifying payment processor communication for all internal services.
Decoupled Card Activation & KYC: Pairs Spring Boot with responsive Thymeleaf user interfaces to execute automated identity verification workflows, resulting in friction-free end-user card activations.
Asynchronous Transaction Processor: Handles real-time ledger payments across Spring Cloud and AWS EC2 instances, leveraging AWS SQS message queues to maintain transaction ordering during traffic spikes.
Dynamic Fee Engine: Automates conditional financial deductions across the payment network, applying custom transaction-level, monthly, and inactivity fees based on corporate card preferences.
Granular Preference & Notification Pipelines: Syncs localized user delivery configurations with an asynchronous notification microservice, transmitting real-time email, SMS, and push transaction updates.
Multi-Tenant Microservices Architecture: Establishes isolated data boundaries across six unified Spring microservices, ensuring secure, isolated transaction monitoring for distinct B2B clients.
The Bottom Line
The System: Delivered a production-ready, six-microservice platform on AWS that handles the end-to-end payment lifecycle from activation to settlement.
The Business: Enabled a US fintech startup to offer white-labeled card issuing capabilities to corporate clients without infrastructural modification.
Technical Stack
Spring Boot
Java8
AWS
PostgresSQL
JavaScript