Backend Engineer

Open to full-time

Bio

John O is a Backend Engineer with over seven years of experience building and scaling production-grade systems across fintech, SaaS, e-commerce, and API-driven platforms. John specializes in TypeScript, Node.js, NestJS, Python, and FastAPI, crafting RESTful and GraphQL APIs that cater to thousands of concurrent users. He is proficient in cloud-native infrastructure and DevOps practices, utilizing AWS and Azure services, Docker, Kubernetes, and CI/CD pipelines to ensure robust deployments. His database expertise includes PostgreSQL, MySQL, MongoDB, and Redis, and he implements event-driven and microservice architectures with RabbitMQ and Apache Kafka. Notable projects include leading the development of 91 Payments, an enterprise-grade currency exchange platform, and Resonate, an AI-driven sermon discovery platform. At Credit Cliq, he built backend systems serving over 10,000 users, integrating APIs with major credit bureaus and ensuring SOC2 compliance. John holds a BSc in Computer Science from Mountain Top University. He is well-suited for roles that involve backend development, API design, and scalable system architecture, particularly in fintech and AI-driven applications.

Expertise

Node.jsMongoDBGraphQLKafkaPythonReactAWSTypeScriptReact NativeNext.jsFast APIKubernetesSQLGitCSSC++Web ScrapingRelational DatabaseDocument DatabaseDatabase Caching

Video Intro

Assessments

General Project Assessment

(91/100)

Implement LRU Cache AlgorithmHard
Understanding Rate Limiting in APIsMedium
Ensuring Real-time Data Accuracy in Mobile AppMedium

Projects

91 Payments - Currency Exchange Platform

91 Pay, is an enterprise-grade, API-first remittance and currency-exchange platform. The platform now enables businesses to move large sums of money globally with transparent, wholesale rates and developer-friendly integrations across six major fiat currencies and USDT.

Resonate - AI-Driven Sermon Discovery Platform

An AI-powered application described as the Shazam for Christian sermons. Users can discover sermon matches and explore a vast library of spiritual messages. I was responsible for the backend and AI services. I made use of Typescript, NestJS, TypeORM, Python, Fast API, LLM integrations and Vector Databases

Gaia AI - AI Powered Matching For Innovators

Gaia AI is a platform that uses AI-powered matching to connect people based on their ideas or projects. It helps users find potential co-founders, collaborators, or supporters who share similar visions for the future. It makes uses of AI to automatically create users profiles. AI powered voice onboarding is built-in, to make the onbaording process seamless and interactive

Experience

Software Engineer
Grey Invent TechnologiesJun 2025 — Present
- Led mobile development for, 91 Payments, fintech app using React Native and Expo, launched to production serving 3,000+ active users across iOS and Android
- Currently leading mobile development for Kloutpay, a creator-focused fintech platform
- Managed deployment pipeline for Google Play Store and Apple App Store releases
- Developed frontend applications and admin panels with Next.js and Tailwind CSS, translating Figma designs into pixel-perfect production interfaces
- Optimized app performance achieving 40% faster load times and 95%+ crash-free rate through efficient state management and code optimization
- Collaborated with QA teams in Agile sprints to ensure quality API integrations and seamless user experience across mobile and web platforms
Node.jsAWSTypescriptAWS AmplifyNext.jsReactReact NativeExpoC#
Software Engineer I
Left Lane TechnologiesOct 2023 — Sep 2025
- Led 5-member engineering team across frontend, backend, and cloud infrastructure, delivering 4 products in fintech, e-commerce, and SaaS with 3x faster shipping velocity
- Architected and developed scalable REST and GraphQL APIs using TypeScript, Node.js, NestJS, Python, and FastAPI serving thousands of concurrent users
- Developed frontend applications with Next.js and TailwindCSS, delivering responsive user interfaces and admin dashboards
- Implemented comprehensive unit testing with Jest achieving 85%+ code coverage, ensuring code reliability and reducing production bugs
- Integrated Stripe and Paystack payment gateways across multiple projects, implementing secure transaction processing and webhook handling
- Designed and implemented microservice architecture using RabbitMQ and FastAPI for async task processing, reducing API response times by 60%
- Managed AWS infrastructure (S3, SES, SNS, Lambda, API Gateway, Elastic Beanstalk, CodePipeline) ensuring 99.9% uptime and scalability
- Oversaw technical communications between engineering teams and management, ensuring alignment on deliverables and sprint goals
TypeScriptNode.jsNestJSPythonFastAPINext.jsTailwindCSSJestStripePaystackRabbitMQGraphQLAWS S3AWS LambdaAWS SESAWS Elastic Beanstalk
Backend Engineer
Credit CliqNov 2023 — Mar 2025
- Integrated APIs with 3 major credit bureaus across US, Canada, and India, ensuring SOC2 compliance and adherence to regional security regulations
- Built backend systems for mobile app serving 10,000+ users, enabling credit report access, identity verification, and credit building through bill payments
- Developed credit-building features allowing users to improve credit scores via airtime purchases and electricity bill payments
- Built robust REST APIs with Node.js, Hono.js, TypeScript, MongoDB, and Redis for efficient credit data processing and real-time identity verification
- Implemented AWS Cognito for secure user authentication and authorization across mobile and admin applications
- Integrated Stripe and Paystack payment services for automated invoice and subscription management
- Developed microservice applications using Apache Kafka, and AWS Lambd for scalablitity when fetching credit reports
- Established CI/CD pipelines with GitHub Actions and AWS CDK for automated deployments and infrastructure management
Node.jsHono.jsTypeScriptMongoDBRedisAWS CognitoStripePaystackApache KafkaAWS LambdaGitHub ActionsAWS CDK