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Olusola Ojewunmi

Senior Backend Engineer · Financial Systems & Multi-Tenant Platforms

I architect the backend systems that companies trust to move money, protect data, and scale without breaking — across fintech, healthcare, logistics, and SaaS.

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Engineering with intent

I build the systems that power products people depend on. Over five years of building in the trenches of production backend engineering, I've shipped 15+ APIs serving real users across fintech, healthcare, logistics, and hospitality.

My work lives at the intersection of domain complexity and engineering discipline — designing state machines, decomposing monoliths into microservices, and architecting event-driven systems that remain coherent under pressure.

I've been the sole engineer who ships, the team lead who unblocks, and the architect who thinks three steps ahead. Whether it's a multi-tenant SaaS platform, a government logistics system, or a healthcare payments engine — I take ownership of outcomes, not just tasks.

5+
Years Experience
15+
Production APIs
6
Industry Domains
90%
Test Coverage Gains
"

Good backend engineering is invisible. Users never think about the API, the queue, or the state machine — they just trust the product.

Domains I've shipped in
Fintech HealthTech Logistics PropTech GovTech SaaS Alumni Tech HR Tech

The stack behind the systems

Production-proven tools from API design to deployment infrastructure.

Backend & Languages
Core engineering stack
PHP Laravel Yii2 Symfony RESTful APIs gRPC Domain Modelling Event-Driven Arch State Machine Design
🗄
Databases & Storage
Data persistence layer
MySQL PostgreSQL MongoDB Redis SQLite Aggregation Pipelines Replica Sets
💳
Payments & Fintech
Financial systems
Paystack Stripe Braintree Remita Virtual Accounts Tokenized Mandates Ledger Reconciliation Dual-Ledger Wallets
🚀
DevOps & Infrastructure
Build & deploy pipeline
Docker GitHub Actions DigitalOcean Linode Linux/Ubuntu Laravel Octane Supervisor Laravel Pulse
📨
Queues & Messaging
Async & event systems
RabbitMQ Apache Kafka Laravel Horizon Supervisor Event Dispatching
🔬
Testing & Observability
Quality & monitoring
PHPUnit Pest TDD Paratest Honeybadger Sentry Datadog Telescope

Where I've built things

A track record of ownership, promotion, and shipping in fully remote, distributed teams.

Senior Backend Developer
Jan 2025 – Present
Squadio (Contract) · Client: ******* — Saudi Hospitality & PropTech · Remote
  • Designed and implemented the OTA integration layer end-to-end — hotel availability, room confirmation, dynamic pricing resolution, and concurrent unit orchestration via DTOs and service abstractions.
  • Architected the bulk offer and discount management system in the pricing microservice, including batch job processing, discount conflict validation, and offer group lifecycle management.
  • Built the performance insights dashboard backend using MongoDB aggregation pipelines with host-scoped authorization and reservation metrics.
  • Raised test coverage from ~5% to ~90% on key services by authoring comprehensive production test suites with DI patterns and MongoDB model isolation.
  • Developed a custom FeatBit PHP SDK for feature flagging across Laravel services, with automated CI via GitHub Actions.
Yii2 MongoDB gRPC Microservices PHPUnit Pest GrowthBook SDK
Engineering Team Lead
Dec 2020 – Present
NQB8 Limited · Product Studio — Promoted from Software Engineer · Remote
  • Send24 (Logistics): Architected entire logistics backend from initial commit — wallet-based payments, WhatsApp-integrated order creation, PDF invoice generation with Google Drive storage, and a role-based operations dashboard.
  • CLRD (GovTech): Designed a microservice-based government logistics regulation platform with RabbitMQ inter-service comms, CAC business verification, Remita payment integration, and QR-based vehicle/rider management.
  • Residifi (PropTech): Built a multi-tenant residential management system with Spatie Multitenancy, Livewire Volt interfaces, visitor access codes, and Excel-based resident import with eager loading.
  • Axocheck (HealthTech): Core feature development including Paystack/Stripe/Braintree integrations and professional payout scheduling.
Laravel PostgreSQL RabbitMQ Docker Livewire Spatie Multitenancy
Backend Developer
Apr 2023 – Apr 2025
Clafiya Limited · HealthTech · Remote
  • Engineered automated wallet top-up and recurring payment systems using tokenized mandates with direct debit, including rollback-safe HSA balance transfers across daily/weekly/monthly cycles.
  • Designed accruing spend limit enforcement for employer-sponsored Health Savings Accounts with sponsor-controlled toggles and monthly carryover logic.
  • Built a Symfony API gateway using API Platform, Doctrine ORM, and JWT authentication for secure third-party API key management.
  • Integrated Kafka-based event dispatching for consultation data sync, plus Typesense full-text search across 75+ models and 144 controllers.
Laravel Symfony Kafka Typesense Google Calendar API Mixpanel
🎓
Bachelor of Science — Computer Science
University of Ibadan
Feb 2016 – Feb 2020 · Ibadan, Nigeria

Products I've owned

End-to-end platforms built from schema to deployment — sole engineer to production.

01 / 03
🏢
Venspace
Space Booking Infrastructure · Sole Architect

Designed and built the entire backend for a two-sided space marketplace from zero — hosts listing spaces, tenants booking them, and payments flowing between both with full financial integrity.

  • State machine-driven booking lifecycle with formal state transitions
  • Dual-ledger wallet with immutable entries for full audit trail
  • Multi-tenant isolation with custom domain DNS verification
  • Rollback-safe payouts that maintain consistency under load
Laravel Spatie Multitenancy Paystack Ably BunnyCDN Laravel Pulse
02 / 03
🔍
Laurel Checks
Employee Verification Platform

Multi-tenant employee background verification platform with Livewire-powered admin interfaces, RBAC enforcement, and asynchronous batch processing pipelines.

  • Async batch import with Excel parsing, chunk processing & row-level error tracking
  • Cloudinary file sync with checksum-based idempotent uploads
  • Downloadable PDF reports for guarantor/referee verification
  • SSH-based deployment automation with backup & env management
Laravel Livewire Spatie Permission Cloudinary DomPDF Maatwebsite Excel
03 / 03
🎓
Alma
Multi-Tenant Alumni Platform API

Full-featured alumni association platform supporting membership management, event organization, job postings, career advice, and social features with per-association data scoping.

  • Ledger-style financials with Paystack: payment intent tracking & audit tables
  • Event-driven subscription lifecycles with dues tracking & payment insights
  • RBAC across 90+ API endpoints via Spatie Permission
  • Auto-generated API docs via Scramble + Laravel Nightwatch observability
Laravel Spatie Multitenancy Paystack Cloudinary Scramble Laravel Nightwatch

How I think in public

Writing about backend systems, engineering judgment, and production lessons learned the hard way.

Numbers that tell the story

Measurable outcomes from production systems, across years of engineering ownership.

⚙️
15+
Production APIs
Shipped across 6 domains
🧪
90%
Test Coverage
Up from ~5% on key services
🏗️
6
Industry Domains
Fintech · Health · Logistics & more
🗂️
5+
Years Remote
Distributed teams globally
Laravel Microservices Event-Driven Architecture Kafka Financial Engineering MongoDB TDD State Machines Multi-Tenancy Docker Laravel Microservices Event-Driven Architecture Kafka Financial Engineering

Let's build something remarkable

Hiring for a backend role? Let's talk about your team and what you're building. Have a specific problem — payments, multi-tenancy, architecture, performance? Bring it.

30 minutes. No small talk.

Come with context — what you're building, what's broken, or what role you're hiring for.

Book 30 mins with Olusola