Slow, risky releases
Monolithic deploys meant months per product and high blast radius on every change.
Case StudyFintechPlatform & BaaS
Core Banking Modernization
Modernizing a legacy core into cloud-native services, opened up as BaaS.
ProjectOverview
A growing financial institution was boxed in by a monolithic core: every new product took months. Zimozi led a phased migration to cloud-native microservices and built an API/Banking-as-a-Service layer, turning the core into a platform that powers embedded-finance partners.
Industry: Bank / Fintech Platform · Region: Singapore & SEA · Services: Core Modernization, Cloud, API/BaaS · Engagement: 14 months (phased). Client identity withheld under NDA; figures representative of the engagement outcome.
TheChallenge
The bank ran on a tightly-coupled legacy core. Releases were big, risky and infrequent; scaling meant scaling everything; and there was no clean way to expose banking capabilities to partners. A full "rip and replace" was too risky, so the bank needed to modernize while staying live.
No partner surface
Banking capabilities were locked inside the core, impossible to offer as clean, governed APIs.
Costly to scale
Vertical scaling of the whole monolith was expensive and inefficient at peak.
Can't stop the business
Migration had to happen with zero downtime and no disruption to live customers.
The Solution
We strangled the monolith and exposed it as a platform.
We mapped the core into bounded domains (accounts, payments, cards, ledger, onboarding), then migrated capability by capability using the strangler pattern: new cloud-native microservices took over behind an API gateway, with zero-downtime cutovers and instant rollback.
An event-sourced ledger and streaming backbone gave consistency, auditability and real-time data across every service, while the legacy core was progressively retired with no big-bang cutover.
On top of the new platform we built a governed, versioned BaaS layer (accounts, payments, KYC, cards) with sandbox and partner onboarding, turning the core into a product other businesses can build on.
KeyFeatures
From a monolithic core to a platform other businesses build on.
01
Domain-driven
Domain-driven
decomposition
Mapped the core into bounded domains, prioritised by business value and risk.
02
Strangler-pattern
Strangler-pattern
migration
New microservices took over capability by capability with zero-downtime cutovers.
03
Event-driven
Event-driven
ledger & data
An event-sourced ledger and streaming backbone gave consistency and real-time data.
04
BaaS &
BaaS &
embedded finance
Governed, versioned APIs with sandbox and partner onboarding built in.
05
Zero-downtime
Zero-downtime
cutovers
Every migration step routed traffic gradually, with instant rollback if needed.
TechStack
Cloud-native microservices, event sourcing/CQRS, Kafka streaming, Kubernetes, an API gateway and a governed Banking-as-a-Service layer aligned to MAS TRM and ISO 20022.
Kubernetes
Kafka
Docker
AWS
Business Impact
A core that accelerates the business.
New products now launch in ~3 weeks instead of ~6 months, with zero-downtime migration throughout. 5+ embedded-finance partners have onboarded onto the new BaaS platform, and infra cost per transaction is down ~45%.
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