Sijuade Ajagunna

Designed and developed an event-driven Mediator service, connecting affiliate sites and embedded sources to the core API, significantly streamlining user interactions and critical event processing.

Led the rapid development of a high-traffic, real-time raffle system, successfully handling over 5,000 concurrent users without downtime and boosting customer engagement.

Re-engineered a legacy betslip service from TypeScript to Elixir, utilizing Elixir processes and ETS to reduce database strain and significantly improve speed, while rewriting the frontend into a standalone microservice and micro-frontend to increase modularity and scalability.

Upgraded a legacy backoffice application by implementing frontend/backend caching, new filtering APIs, and lazy loading with Node.js and React, enabling efficient management of over 57,000 categories.

Migrated legacy React applications to Next.js microservices within a monorepo architecture, enhancing application performance and developer productivity.

Managed the migration of the company's KYC service to a new provider, maintaining 100% uptime and preserving critical customer data integrity throughout the transition.

Mentored junior engineers through comprehensive code reviews, pair programming, and constructive feedback, fostering team collaboration and elevating code quality.

Engineered a robust student/instructor onboarding platform with integrated payment processing via Stripe, Paystack, and Flutterwave APIs, successfully handling over 50,000 transactions with 99.9% uptime.

Designed and implemented a scalable microservices architecture for course management, user authentication, and payment processing, ensuring modularity and independent scalability across the platform.

Developed webhook handlers and event-driven systems utilizing Amazon SQS message queues for asynchronous payment notification processing and course enrollment automation, reducing manual processing time by 80%.

Established automated CI/CD pipelines using AWS ECS, Fargate, and CodeDeploy with Docker containerization, enabling multiple daily deployments with robust rollback capabilities.

Implemented comprehensive API documentation using Swagger/OpenAPI and established unit and integration testing practices with Jest, achieving over 85% code coverage.

Built and maintained backend APIs and integrations for customer feedback, complaints management, and internal tools, enhancing operational efficiency and user satisfaction.

Developed a comprehensive Customer Relationship Management (CRM) application that streamlined talent registration and hiring processes, improving data management and workflow automation.

Created and deployed a custom CMS with Ghost for managing internal and client-facing content, leveraging Amazon RDS as the primary data store.

Managed the CI/CD pipeline for web applications using AWS CodeBuild, ECS, CodePipeline, and Cloudflare, ensuring continuous integration and efficient deployment.

Led the project from initial client requirements gathering to final delivery, coordinating a team to ensure successful execution.

Proactively addressed client-reported issues through efficient bug fixes, enhancing the overall quality and reliability of delivered solutions.

Successfully migrated over 20,000 users from a legacy application to the new version, ensuring data consistency between different database systems.

Developed responsive and reactive front-end applications as a full-stack developer using Next.js, TypeScript, and GraphQL with Apollo Federation.

Designed and developed secure RESTful APIs using Node.js/TypeScript and Adonis.js, implementing JWT authentication and input validation to prevent security vulnerabilities.

Architected and modeled SQL schemas to support dynamic user profiles, region-based content delivery, and multi-tenant data isolation across diverse client applications.

Built rate-limiting and API throttling mechanisms using middleware to protect endpoints from abuse and ensure fair resource usage across clients.

Implemented comprehensive end-to-end testing strategies using Jest and Postman, achieving 80%+ test coverage and automating API documentation with Swagger/OpenAPI specifications.

Optimized database queries and implemented indexing strategies, reducing average API response times from 800ms to under 200ms, a 75% improvement.

Collaborated with cross-functional teams (product managers, frontend developers, QA) in agile sprints to refine requirements and technical specifications, reducing feature rework by 30%.