Battle-tested architecture patterns for building regulated financial systems.
Distilled from 17 years of building payment systems, trading platforms, and fintech scale-ups at BNP Paribas, Société Générale, Crédit Agricole, and startups across Europe and the Middle East.
| Pattern | Description | Regulations |
|---|---|---|
| Payment Orchestration | Coordinating multi-provider payment flows with fallback and retry | PCI DSS, PSD2 |
| Compliance Event Sourcing | Immutable audit trails for regulatory reporting | GDPR, SOX, MiFID II |
| Multi-Tenant Banking | Isolating customer data in BaaS platforms | Data residency, GDPR |
| Regulatory Audit Trail | Complete transaction lineage for regulators | All |
- Fraud Detection Pipeline
- KYC/AML Integration
- Real-Time Balance Management
- Cross-Border Payment Routing
Common mistakes I've seen (and made) in fintech systems:
| Anti-Pattern | Why It's Dangerous |
|---|---|
| Shared Database for Tenants | One breach exposes all customers |
| Synchronous Payment Processing | Timeout = lost transaction = angry customer |
| Audit Logs as Afterthought | Regulators will find gaps |
| Homegrown Encryption | You will get it wrong |
Use these patterns as starting points for architectural discussions. Each pattern includes:
- Problem context
- Solution overview
- Trade-offs
- Implementation considerations
- Regulatory implications
Each pattern includes diagrams and pseudocode. Adapt to your stack and context.
Reference these patterns when evaluating fintech technical architecture.
Each pattern follows this structure:
patterns/[pattern-name]/
├── README.md # Full pattern documentation
├── diagram.md # Mermaid diagrams
├── implementation.md # Pseudocode and considerations
└── checklist.md # Validation checklist
Found a pattern missing? Have a war story to share?
- Open an issue to discuss new patterns
- PRs welcome for improvements and corrections
- Share your anonymized case studies
Created by Khaled Souf — Fractional CTO for Fintech.
I help fintech founders build systems that scale and pass regulatory scrutiny.
- Fintech CTO Checklist — Pre-seed to Series A readiness
- DDD Europe Workshop — Domain-Driven Design in practice
MIT — Use freely, attribution appreciated.
"The best architecture is the one that lets you sleep at night — especially when you're processing other people's money."