Previously on NEXT: Banks are losing their grip on customer relationships as fintech platforms and embedded services disintermediate traditional channels. The core banking system is no longer a differentiator—it's either a burden or a launchpad. In Episode 1, we explored why the great unbundling of financial services has forced banks to rethink their digital DNA. Now, we ask: how do you actually build for that future?
For decades, traditional core banking systems were built as massive, vertically integrated stacks. Everything from deposits and lending to compliance and risk lived in one fortress. These systems were robust, but brittle. Expensive to change, slow to integrate, and allergic to innovation.
But the world outside changed.
As customers began to expect real-time services, seamless UX, and product variety, banks discovered that a single, monolithic system couldn't keep up. Every change required a release cycle. Every innovation came with regression risk. Business and IT were locked in a waterfall embrace.
Composable banking breaks that cycle.
Think of composable banking as a bank built from Lego bricks, not poured concrete.
Each capability—onboarding, payments, credit decisioning, customer insight, ESG scoring—is a module. These modules are reusable, replaceable, and connect via APIs, events, and services. That means:
Banks can swap out or upgrade a part without disrupting the whole.
Services can be reused across journeys, brands, or regions.
New features can be assembled fast from existing building blocks.
The result? Speed, agility, and scale.
Composable doesn't mean chaos. It means clear boundaries, clean architecture, and autonomy. And it's not a future trend. It's happening now.
SAP’s approach to composable banking starts with a deceptively simple philosophy: "Keep the core clean."
The idea: Don't turn your ERP or core banking system into a Frankenstein monster of local extensions and quick fixes. Instead, build new innovations side-by-side using SAP BTP (Business Technology Platform). Connect via APIs and events. Leave the core stable, secure, and upgradable.
This is more than theory. It's architectural discipline.
According to SAP Fioneer, banks using side-by-side extensions have reduced change delivery times by over 60% while improving auditability and scalability[1].
Here’s how it comes together:
| Component | Role |
|---|---|
| SAP TRBK (Transactional Banking) | Cloud-native, componentized core for deposits, lending, accounts |
| SAP BTP | Side-by-side extension layer for innovation, APIs, workflows, and AI integration |
| Event Mesh | Real-time, event-driven communication across services |
| Integration Suite | Out-of-the-box connectors to fintechs, payments, partners |
| SAP Joule & AI Foundation | Embedded AI for decisions, recommendations, and automation |
With this stack, banks can:
Launch products without touching the core
Automate onboarding, KYC, or loan origination
Integrate external data sources and fintech services
Build AI-driven workflows with explainability baked in
Let's say your bank wants to launch a green lending product tied to ESG scoring. In a traditional system, that might take 12+ months.
With a composable stack:
Use TRBK to manage the product and lifecycle.
Integrate a third-party ESG scoring engine via API.
Build an onboarding journey with SAP Build Apps.
Trigger workflows via Event Mesh when applications are submitted.
Use Joule AI Agents to screen for compliance or fraud signals.
Time-to-market? 8–12 weeks.
As noted in the SAP Fioneer Partner Kickoff 2025, several regional banks are already achieving this velocity[1].
Composable architectures need composable governance. That means:
Defining ownership per module (who maintains what?)
Clear API versioning and documentation
Platform engineering teams to maintain shared capabilities
DevSecOps to automate testing, security, and release
SAP BTP enables all of this with policy-based access control, centralized monitoring, and lifecycle management.
Composable isn't plug-and-play. It's design with discipline.
When regulators introduce a new rule, composable banks respond in weeks, not quarters. When a fintech partner changes APIs, you only adapt the integration module. When AI becomes a compliance requirement (and it will), you plug in explainability modules rather than rebuild the engine.
Composable = anti-fragile.
In a market where change is accelerating, modular banks don't just survive. They adapt, absorb, and grow stronger.
At Fixtra, we help financial institutions adopt composable principles using SAP BTP, TRBK, and AI-native workflows. Our architects and designers build modular platforms that don’t just integrate—they evolve. Composability is not about speed alone. It's about the confidence to change, again and again.
In Episode 3, we explore the human side of digital finance. If composability is the "how," then hyper-personalization is the "why." What happens when your bank starts predicting behaviors—and acting on them in real-time?