Abdulbasit Quadri

Senior Full-Stack Engineer with 7+ years delivering production-grade fintech, travel-tech, and logistics platforms across the complete stack. Deep expertise in React/Next.js, Node.js/NestJS, PostgreSQL, Redis, and AWS. Hands-on experience engineering distributed payment systems including idempotency, double-debit prevention, fraud detection pipelines, reconciliation, and Saga-pattern distributed transactions.

Track record of architecting real-time, high-availability systems for large user bases across Africa, with a strong focus on payment integrity, system resilience, and engineering excellence.

Senior Full-Stack Engineer at Gopaddi (2024-08 – Present)

• Architected the full-stack platform across all three Gopaddi verticals — consumer app, corporate travel dashboard, and supplier marketplace — using React.js/Next.js frontends and Node.js/NestJS microservices, with shared component libraries and a unified API gateway
• Engineered idempotency-safe payment flows across flight, hotel, restaurant, and event bookings — assigning unique idempotency keys per transaction attempt so that network retries and client re-submissions never result in double debits
• Implemented distributed transaction handling using the Saga pattern — chaining booking confirmation, payment debit, and supplier notification as sequential steps with compensating rollback actions (auto-refund + cancellation) if any downstream service failed
• Built a real-time fraud detection layer on the payment pipeline — scoring each transaction against velocity signals (txn count per hour), geographic anomalies, and device fingerprinting before authorization, blocking high-risk payments in under 100ms
• Designed and automated a nightly reconciliation job comparing internal booking ledger records against payment processor settlement reports — flagging missed debits, duplicate credits, and unmatched transactions for analyst review before settlement
• Built Paddi AI travel assistant and collaborative Trip Planner with payment-split functionality — users co-plan trips and divide costs in real time, backed by Node.js APIs, Redis session state, and WebSocket sync across participants
• Integrated RESTful and GraphQL APIs with third-party booking providers and payment gateways, handling supplier inventory, live availability, pricing, and reservation confirmation flows
• Provisioned and managed AWS infrastructure (EC2, S3, RDS, Lambda, CloudWatch) with GitHub Actions CI/CD, achieving zero-downtime deployments and high availability for booking-critical services
• Implemented OAuth 2.0/JWT authentication with role-based access control across consumer, corporate, and supplier portals — enforcing data isolation between platform verticals
• Reduced app load time by ~40% via React code splitting, SSR optimization, and backend query tuning; built React Native mobile app increasing user retention by 30%
• Mentored junior engineers, led code reviews, and established engineering standards across frontend and backend squads

Full-Stack Engineer at Figo Africa (2022-11 – 2025-02)

• Built full-stack features for Figo's core fintech platform — React.js/Next.js frontends and Node.js/Express.js backend APIs supporting digital payments, wallet management, fund disbursements, and HR/payroll workflows for a large active user base
• Engineered idempotent payment APIs — every fund transfer and payroll disbursement carried a unique idempotency key, preventing double payments when clients retried failed requests over unstable network connections
• Implemented optimistic locking on wallet balance updates — using database version checks to prevent race conditions where concurrent debit requests could overdraw accounts under high load
• Built a transaction reconciliation module that compared internal payment records against bank statement feeds daily — surfacing discrepancies (missing credits, unrecorded debits) and generating exception reports for the finance team
• Integrated a rule-based fraud detection layer on payment endpoints — blocking suspicious transactions based on velocity thresholds (e.g. multiple high-value transfers within minutes), flagging anomalous patterns for compliance review
• Integrated AI-driven modules into financial and HR workflows — automated payroll processing, intelligent spend categorization, and AI-assisted employee management interfaces that reduced manual processing time significantly
• Designed backend data models and REST APIs in Node.js/PostgreSQL with ACID-compliant transactions, ensuring financial data integrity across all fund movement operations
• Implemented OAuth 2.0 and JWT with role-based access control, maintaining compliance with Nigerian financial data security and CBN regulatory standards
• Optimized frontend performance with SSR (Next.js), Redux memoization, and React.memo — reducing re-renders and improving dashboard load times across financial reporting views
• Diagnosed and resolved production incidents affecting financial transactions, conducting root cause analysis and implementing safeguards to prevent recurrence

Frontend Engineer (Full-Stack Contributor) at SameDay Custom (2018-03 – 2022-10)

• Built cross-platform trading and logistics applications in React, React Native, and TypeScript — supporting real-time order transactions, live delivery tracking, and partner fulfilment operations across iOS and Android
• Expanded into backend development — built and maintained Node.js APIs and GraphQL endpoints powering the order routing engine, which matched incoming orders to available local print partners based on real-time capacity, distance, and SLA
• Implemented idempotent order submission endpoints — preventing duplicate orders from being created when customers re-submitted on network timeout, a critical reliability requirement for same-day fulfilment SLAs
• Built real-time order tracking and live status push updates using WebSockets — customers received instant notifications at each fulfilment milestone (accepted, printing, ready, dispatched), reducing support ticket volume
• Optimized GraphQL data fetching with query batching and DataLoader, reducing API latency by ~20% and improving responsiveness under high concurrent order volumes
• Implemented secure API authentication and authorization flows, ensuring tamper-proof order processing and protecting customer payment data
• Collaborated with design, backend, and product teams in Agile sprints to iteratively deliver new delivery verticals, print product types, and platform features

Bachelor's Degree in Electronics And Computer Engineering – Lagos State University (2016-08 – 2021-11)