I build the systems behind products people depend on.
Node.js · TypeScript · NestJS · PostgreSQL · Redis · Payments · APIs
I design and build backend systems for marketplaces, payments, operations, healthcare, and data-heavy products — APIs, workflows, databases, webhooks, real-time features, and production reliability.
Backend work across products with real operational complexity.
These case studies focus on the systems I built or contributed to, the decisions behind them, and the constraints that shaped the implementation.
Roomfit
Backend Engineer / Product Builder
A room, property, and roommate marketplace supported by a versioned NestJS backend serving web and mobile clients with real-time messaging and Paystack billing.
Key Architecture & Systems
- •Designed and implemented modular NestJS REST APIs serving both mobile (bearer token) and web (cookie/session) clients.
- •Engineered the complete listing lifecycle including drafts, validation rules, media uploads, location indexing, and publication gating.
- •Integrated Socket.IO for private real-time messaging, unread counts, and active state synchronization.
Vouch Express
Backend Engineer / Contributor · Vouch Africa
A fintech platform supporting payments, digital wallets, merchant onboarding, transaction verification, and guarantee-based financial workflows.
Key Architecture & Systems
- •Contributed to backend Node.js microservices handling core payment processing, wallet balance management, and merchant accounts.
- •Implemented robust API validation pipelines ensuring strict request payloads before processing monetary transactions.
- •Integrated third-party payment providers and banking APIs for virtual account generation and payout settlements.
Additional Systems & Operational Work
Focused backend engineering contributions across logistics, pharmacy digitization, IoT hardware telemetry, and automated financial research.
Wancemo
Backend Engineer / Team Contributor · Wancemo South Africa
Operations software for waste collection, storage tracking, driver/team coordination, status workflows, and administrative visibility across South African municipalities.
Highlights
- •Built and maintained NestJS microservices and PostgreSQL data models for collection records, facility inventories, and driver schedules.
- •Engineered workflow state transitions (Scheduled -> En Route -> Collected -> Deposited -> Verified) with input validation at every step.
Ngoane Health
Backend Engineer / Software Contributor · Ngoane Health
Backend systems powering RxKonet (community-pharmacy inventory and dispensing) and myRx (patient health management and prescription fulfillment).
Highlights
- •Contributed backend APIs for pharmacy inventory tracking, medication catalog search, and prescription fulfillment lifecycle.
- •Engineered role-based access controls ensuring patients can only view their own health records while pharmacists access authorized dispensing queues.
IoT Electricity Monitoring
Software / IoT Engineer
A real-time electricity monitoring platform connecting ESP32 embedded energy metering hardware to AWS IoT Core, time-series storage, and a live web dashboard.
Highlights
- •Configured ESP32 firmware network protocols and MQTT message topic hierarchies for hardware telemetry transmission.
- •Engineered Node.js telemetry ingestion microservices connected to AWS IoT Core MQTT message broker.
Trading Automation Platform
Independent Backend Project
A configuration-driven trading research and execution backend for market-data ingestion, strategy testing, paper execution, and controlled live exchange integrations.
Highlights
- •Engineered Python data ingestion pipelines downloading historical candles, trades, and orderbook snapshots into SQLite / Pandas datastores.
- •Built normalized exchange adapter classes unifying ticker symbols, order placement DTOs, and balance responses across Bybit, Bitget, and BingX.
The parts of product engineering I work closest to.
System architecture, data integrity, security boundaries, payment reliability, and real-time operational workflows.
Modular REST APIs, NestJS architecture, service boundaries, strict request validation, versioning, error contracts, and unified APIs serving web, mobile, and third-party clients.
PostgreSQL and SQL-backed domain models, relational schemas, Prisma & raw SQL queries, state transitions, indexing, soft-deletes, and reporting-friendly data structures.
JWT and session-based authentication, HTTP-only cookies, mobile bearer tokens, Role-Based Access Control (RBAC), ownership checks, and protected resource guards.
Paystack checkout integrations, transaction verification, signed HMAC webhooks, recurring and one-time subscription billing, callback reconciliation, access periods, and payment recovery.
Socket.IO messaging gateways, MQTT hardware telemetry pipelines, push/email notification triggers, scheduled maintenance tasks, and event-driven integration patterns.
Backend engineering is mostly about making state, failure, and responsibility explicit.
The backend owns business truth
“Clients render state; they should not independently invent payment, access, or workflow rules.”
Frontend and mobile clients are visual views into the system. All authorization, subscription access, state transitions, and validation rules are calculated and enforced strictly on the server.
Every state needs a recovery path
“Pending, failed, expired, cancelled, and partially completed operations should lead to a safe next action.”
Distributed interactions fail in unpredictable ways. Systems must be designed with explicit status enums, retry mechanisms, verification endpoints, and graceful fallbacks.
Integrations are unreliable boundaries
“Webhooks can arrive late or repeatedly. Networks fail. Callbacks race. External systems must be verified and reconciled.”
Never trust third-party events blindly. Always verify webhook signatures (HMAC), enforce strict idempotency checks on transaction IDs, and maintain background polling reconciliation routines.
Maintainability is part of delivery
“Clear modules, typed contracts, validation, logs, tests, and documentation reduce the cost of future changes.”
Backend code is written once but read, debugged, and extended many times. Clean domain separation, strict DTO schemas, and structured logging make production operations predictable.
Four years across marketplace, fintech, healthcare, operations, and connected systems.
Backend Engineer / Product Builder
Roomfit
PropTech & Marketplace platform for property listings and roommate matching in Nigeria.
- •Architected versioned NestJS REST backend serving React Native mobile and Next.js web applications.
- •Implemented real-time private chat using Socket.IO, message persistence, and delivery fallback notifications.
- •Built automated Paystack payment pipeline for Premium subscriptions, handling signed HMAC webhooks and idempotency checks.
- •Optimized listing search and filter queries in PostgreSQL with multi-column composite indexing.
Backend Engineer / Contributor
Vouch Africa (Vouch Express)
Fintech platform powering digital wallets, merchant onboarding, and payments.
- •Contributed Node.js backend microservices for core merchant wallets, payout disbursements, and ledger transactions.
- •Integrated distributed Redis mutex locks to enforce atomic balance operations across concurrent disbursement attempts.
- •Built KYC compliance pipelines for merchant identity verification and tier-based transaction limits.
- •Handled background status reconciliation loops for third-party banking provider webhooks.
Backend Engineer (Contract)
Wancemo
Municipal & commercial waste management logistics software in South Africa.
- •Designed NestJS microservices and PostgreSQL schemas for field collection logging and depot storage tracking.
- •Implemented strict state machine transitions enforcing valid status progression across collection crews.
- •Engineered batch payload endpoints allowing offline mobile driver queues to sync upon signal restoration.
Backend Engineer (Contract)
Ngoane Health
Digital healthcare infrastructure supporting RxKonet pharmacy management and myRx patient portal.
- •Developed APIs for pharmacy inventory management, drug dispensing records, and patient prescription refills.
- •Enforced strict role-based access control ensuring patient Health Identifiable Information (PHI) remained strictly isolated.
- •Implemented custom log formatters stripping sensitive patient data prior to log aggregation streams.
Software / IoT Engineer
IoT Electricity Monitoring
Embedded ESP32 energy hardware telemetry connected to cloud ingestion and live monitoring dashboard.
- •Configured ESP32 firmware MQTT telemetry publishing to AWS IoT Core over mutual TLS authentication.
- •Built Node.js telemetry consumer downsampling high-frequency power readings into PostgreSQL time-series tables.
- •Streamed near-real-time electrical telemetry updates to monitoring web dashboards via WebSockets.
Independent Developer
Trading Automation Backend
Configuration-driven crypto exchange data ingestion and quantitative strategy execution engine.
- •Built unified Python exchange adapters wrapping Bybit, Bitget, and BingX REST/WebSocket APIs with HMAC signing.
- •Designed Pandas and SQLite data pipelines for tick-to-candle aggregation and strategy backtesting.
- •Engineered hard risk controls including maximum order sizing, balance checks, and panic kill-switch daemons.
A product-minded backend engineer who likes understanding the whole system.
I started building software in 2022 and have worked across marketplace, fintech, healthcare, operations, IoT, and automation products. My strongest day-to-day work is in backend engineering: translating product requirements into data models, APIs, workflows, integrations, and reliable state transitions.
I am comfortable entering an existing codebase, tracing business logic, debugging data and API problems, documenting what the system actually does, and improving it in controlled steps. I also enjoy collaborating closely with frontend, mobile, product, and operations teams because many backend problems only become clear when the entire user journey is understood.
- •PostgreSQL deep execution plan tuning & indexing
- •Redis distributed caching & mutex lock patterns
- •Automated integration testing & CI/CD pipelines
- •Cloud-native reliability & systems operating at scale
Let’s talk about backend systems, product engineering, or an open role.
The fastest way to reach me is by email. I am open to backend engineering opportunities, thoughtful collaborations, and conversations about the systems shown here.