Technology &
Architecture
Financial technology infrastructure fails slowly and expensively. The decisions made in the first years of a platform's life — about data models, API contracts, processing architecture, and vendor integration patterns — create constraints that persist for decades. Getting them right requires both technical depth and product leadership perspective.
Platform Architecture
Designing payment and financial services platforms requires balancing the need for operational resilience with the flexibility to evolve products and markets over time. The choice between monolithic and microservices architectures, event-driven versus request-response processing models, and the selection of data persistence strategies all have implications that extend far beyond the first release.
Subite's architecture advisory is grounded in operational experience with real payment systems at scale — combining product management perspective, operations leadership, and deep technical understanding. Not pattern catalogues applied from the outside.
- Payment platform architecture design and independent review
- Event-driven architecture patterns for financial services
- High-availability and disaster recovery design for regulated systems
- Data model design for payment and ledger systems
- Build vs buy analysis for core platform components
- Technical due diligence for investors and acquirers
- Platform scalability assessment and roadmap design
Legacy Modernisation
Replacing a core payment system or banking platform while it continues to process millions of transactions daily is one of the highest-risk programmes a financial institution can undertake. The technical migration strategy is only part of the challenge — the programme governance, the risk management, and the organisational change are equally important.
Legacy modernisation in financial services is not a technology problem — it is a risk management challenge that happens to involve technology. The systems that need replacing are often the ones that process millions of transactions daily and touch every other system in the estate.
- Legacy assessment and modernisation strategy design
- Strangler fig migration pattern design and implementation advisory
- Data migration strategy and risk assessment
- Parallel running and cutover planning
- Programme governance design for core replacement projects
- Vendor selection and contract advisory for replacement programmes
- Rollback strategy and contingency planning
API Strategy
For financial services companies, API strategy is simultaneously a product decision, a security decision, and a regulatory decision. Open banking APIs carry specific technical standards; partner APIs carry commercial implications; internal APIs define the boundaries of the system's evolution.
API design decisions made early tend to be expensive to reverse — particularly in regulated environments where external parties have contractual or regulatory dependencies on API contracts.
- Open banking API design and compliance review (Berlin Group, STET, UK Open Banking)
- API gateway selection and implementation advisory
- Developer portal strategy and documentation design
- API security architecture — OAuth 2.0, mTLS, certificate management
- API versioning and deprecation strategy
- Third-party provider onboarding framework design
- API product commercial modelling
System Integration
Payment systems sit at the centre of complex integration topologies — core banking systems, card management platforms, scheme interfaces, regulatory reporting systems, and a growing ecosystem of third-party service providers. Integration strategy shapes both operational complexity and the pace at which the business can evolve.
The integration challenges in financial services are compounded by the mix of modern APIs and legacy message formats, real-time and batch processing requirements, and the reliability expectations of regulated systems.
- Integration architecture design for payment ecosystems
- Core banking integration patterns for payment systems
- Payment switch connectivity and message format strategy (ISO 8583, ISO 20022)
- Third-party service orchestration — fraud, identity, compliance tooling
- Message queuing and event streaming architecture (Kafka, RabbitMQ patterns)
- Integration monitoring and observability design
- Integration testing strategy for regulated systems