Senior Backend Engineer & Platform Architectfor payment systems that can’t afford to fail
4+ years building production-grade distributed systems across fintech, core banking, payments, SaaS and blockchain — Java Spring Boot 3, NestJS, Fastify, Apache Fineract, Azure Service Bus, and immutable ledger architecture.
Built systems at
Samuel Nwabueze
4+
Years production
99.9%
Uptime SLOs
35%
Latency reduced
60%
Abuse eliminated
Specialisation
Engineering focus
Where I spend most of my time — building systems that stay reliable under pressure.
Payment Systems
Idempotent webhook pipelines, Paystack & Flutterwave integrations, fraud detection APIs.
fintechDistributed Architecture
Multi-tenant platforms, event-driven microservices, domain-driven design with strict boundaries.
infraAPI Design
RESTful APIs, JWT / OAuth2 auth, rate limiting, versioning, OpenAPI documentation.
platformSecurity & Compliance
Vault-managed secrets, OIDC / RBAC, encrypted data at rest, PCI-aware patterns.
securityApproach
How I build
Reliability patterns
Idempotency keys, outbox/event replay safeguards, and dead-letter recovery built into every write path.
retry-safeProduction discipline
Domain boundaries, async queue orchestration, and versioned API contracts for long-term maintainability.
api versioningObservability-first
Trace-aware logs, failure classification, and operational dashboards tied to business-critical flows.
slo-drivenCase Studies
Systems I’ve built
System Design
Architecture at a glance
A simplified view of a payment processing pipeline — the kind of systems I design and build.
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Payment systems, core banking, distributed architecture — practical posts from production, not theory.
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Writing
Latest articles
Designing Idempotent Payment Systems
Why idempotency keys are non-negotiable in financial APIs and how to implement them correctly in Spring Boot and NestJS.
3 min read
Webhook Reliability at Scale
Patterns for exactly-once processing, dead-letter queues, and retry back-off in payment webhook pipelines.
3 min read
Open Source
Key projects
Let’s build something reliable
Open to contract work, full-time senior roles, and technical advisory. Let’s talk about your infrastructure challenges.
$ delivery-plan --next-90-days
1. architecture deep-dive
2. reliability hardening sprint
3. performance & cost profiling
4. production rollout + observability