
Olarewaju Akeem Opeyemi
Verified Expert in Engineering
Full-stack Developer
Lagos, Nigeria
Toptal member since August 4, 2021
Opeyemi is a senior full-stack engineer specializing in high-performance web applications built with React, Node.js, and TypeScript. He has delivered scalable, responsive platforms used by thousands of users, focusing on performance optimization and real-time user experiences. Opeyemi builds clean, reliable interfaces that help teams ship faster and scale confidently
Portfolio
Experience
- Redux-Saga - 10 years
- JavaScript - 10 years
- React - 10 years
- Redux - 9 years
- TypeScript - 9 years
- Next.js - 8 years
- Material UI - 5 years
- Gatsby - 2 years
Preferred Environment
Jira, Docker, Blockchain, Capacitor, Artificial Intelligence (AI), Node.js, React, Python, TypeScript, React Native
The most amazing...
...projects I've collaborated on included a React Native-based investment mobile app for Africans and a React-based web KYC app built for chats and video calls.
Work Experience
Senior Full-stack Engineer
cashandchat
- Designed and developed a real-time chat platform enabling paid interactions for use cases such as consultation, counseling, and social engagement.
- Built cross-platform web and mobile applications using React, React Native, and Capacitor.js, ensuring seamless user experience across devices.
- Implemented real-time communication systems using WebSockets, Socket.IO, and Simple-Peer (WebRTC), enabling low-latency messaging and video interactions.
- Developed back-end services with Node.js and Parse Server, handling authentication, user sessions, and real-time data synchronization.
- Designed a scalable front-end architecture with TypeScript and Material UI, improving maintainability and UI consistency.
- Optimized real-time data flows and UI updates, ensuring responsive performance under concurrent user activity.
- Navigated platform compliance challenges (App Store policies), gaining experience in product constraints, risk assessment, and platform governance.
Senior Front-end Engineer
Tropic Seascape Pte Ltd
- Built a platform from scratch where new games in the NFT world can launch their application and participate in lotteries at seascape.house using Next.js for the UI and ether packages for wallet connections.
- Built a platform from scratch for the Blocklords game, where gamers can track and buy NFTs and participate in lotteries and special offers at blocklords.com using Next.js for the UI and IMX and ether packages for wallet connections and NFT transactions.
- Managed and maintained an existing Gatsby application using WordPress API with the gatsby-source-wordpress plugin.
- Developed a large-scale NFT marketplace using React and TypeScript, supporting 200,000+ users and enabling real-time asset trading across blockchain networks.
- Integrated blockchain transaction flows using Ethers.js and Immutable X, improving wallet connection success rates and reducing onboarding friction.
- Optimized UI rendering and data synchronization for high-frequency blockchain updates, improving responsiveness by around 40% under peak load.
- Designed a front-end architecture for transaction flows aligned with smart contracts, reducing failed transactions and improving system reliability.
- Collaborated with cross-functional teams to deliver scalable features supporting multi-game ecosystems and increasing user engagement.
Full-stack Developer
Ejobkit
- Managed a team of front-end developers to build a sleek, responsive, and attractive landing page using Material-UI with captivating React features that met SEO standards (used Gatsby).
- Led a team of front-end developers to build a section of an application dashboard where clients, freelancers, and affiliates can interact and also manage their accounts using React and TypeScript.
- Oversaw a team of back-end developers to build a back end that accommodates the application's mobile and web users using Parse Server.
- Built a multi-tenant freelance marketplace platform supporting thousands of concurrent users with real-time interactions across client and freelancer workflows.
- Developed responsive front-end interfaces using React and Gatsby, improving SEO performance and increasing organic traffic by over 50%.
- Implemented role-based dashboards and optimized API orchestration, improving data retrieval efficiency and user experience.
- Managed complex asynchronous flows using Redux-Saga, ensuring stable real-time behavior and reducing front-end defects.
- Integrated back-end services using Node.js and Parse Server, creating a unified API layer across web and mobile platforms.
- Introduced end-to-end testing with Cypress, improving release reliability and reducing regression issues.
React and React Native Developer
Rise
- Managed a team of front-end developers to build and manage a fast investment mobile application using React Native and TypeScript.
- Led a team of front-end developers to build a customer management tool that assisted staff with interacting with investors and taking admin actions such as editing user profiles, payments, and withdrawals on behalf of investors.
- Oversaw a team of front-end developers to build a platform affiliate program dashboard where affiliates can see their earnings and track their progress.
- Developed a cross-platform investment application using React Native, supporting thousands of users and improving transaction speed and reliability.
- Built real-time dashboards for internal operations, enabling transaction monitoring and improving operational efficiency for support teams.
- Implemented affiliate and analytics platforms to track user acquisition and conversion flows, supporting business growth initiatives.
- Optimized API integration and asynchronous data handling, reducing latency by around 30–40% and improving application responsiveness.
- Improved mobile stability by addressing performance bottlenecks, reducing crash rates and enhancing user experience across iOS and Android.
Web Engineer
Numbrs
- Built a WebRTC-based KYC communication platform enabling real-time video and chat for identity verification at scale.
- Developed scalable front-end systems using React and TypeScript, improving onboarding flow efficiency and user completion rates.
- Implemented reusable component architecture, accelerating feature delivery and ensuring UI consistency across products.
- Introduced testing practices that reduced defects and improved system stability in production environments.
Full-stack Developer
Online Freelance Agency
- Contributed to full-stack web applications using JavaScript, Node.js, and modern front-end frameworks.
- Built reusable UI components and integrated back-end APIs, improving development efficiency and code reuse.
- Collaborated in agile teams, delivering features in fast-paced development environments.
GIS/Web Developer
GIS
- Developed web applications using HTML, CSS, and JavaScript, building foundational front-end engineering skills.
- Worked on GIS-based web solutions, integrating mapping data and improving user interaction with location-based services.
- Improved company revenue with optimized mapping and GIS architecture.
Experience
A Game's NFT Management Application
https://blocklords.comA Game Launch Project for NFT Game Developers
US Investing for Africans
Real-time Investment Platform (Web & Mobile)
http://www.rise.capitalWebRTC-based KYC Verification Platform
Implemented WebRTC-based peer-to-peer communication and integrated real-time messaging using WebSockets. Developed scalable front-end architecture using React and TypeScript, ensuring smooth user interaction and consistent performance during live sessions.
Optimized connection stability and user experience, significantly improving verification completion rates and reducing onboarding friction for financial applications.
NFT Marketplace for Real-time Digital Asset Trading
https://www.seascape.networkMulti-tenant Freelance Marketplace Platform
Developed responsive front-end interfaces using React and Gatsby, improving SEO performance and increasing organic traffic. Implemented role-based dashboards and optimized API orchestration for efficient data retrieval.
Integrated back-end services using Node.js and Parse Server, enabling seamless communication across web and mobile clients while maintaining system scalability and reliability.
Real-time Paid Chat & Consultation Platform
Integrated WebRTC-based communication using Simple-Peer to support live interaction features. The project was discontinued due to App Store policy restrictions, but demonstrated strong capabilities in building real-time, scalable communication systems.
Education
Bachelor's Degree in Computer Science
Federal University of Agriculture Abeokuta - Abeoukuta, Ogun State, Nigeria
Certifications
Meta Front-end Developer Professional Certificate
Meta
Ethereum Developer Certification – Consensys
Consensys
Skills
Libraries/APIs
Redux-Saga, Redux Form, React, Socket.IO, Node.js, WebRTC, Web3.js, jQuery, React Redux, Redux Router, GraphQL API, Natural Language Toolkit (NLTK)
Tools
Slack, Create React App, Capacitor, Figma, Xcode, Android Studio, Git, GitHub, MetaMask, Jira, Postman, Redux Toolkit, GIS, GitHub Copilot, Sequelize
Languages
JavaScript, TypeScript, HTML, CSS, HTML5, Java, GraphQL, CSS3, Python, SQL
Frameworks
Redux, Material UI, Next.js, React Native, Flux, Cypress, Express.js, Jest, Tailwind CSS
Platforms
Parse Server, MacOS, Visual Studio Code (VS Code), Ethereum, Blockchain, Docker
Paradigms
REST, Agile
Storage
PostgreSQL, MongoDB
Other
Gatsby, APIs, User Interface (UI), Front-end, WebSockets, Full-stack, Startups, API Integration, Styled-components, Ethers.js, Ethereum Smart Contracts, Immutable X, Cryptocurrency Wallets, Gaming, Casinos & Gaming, Server-side Rendering (SSR), CI/CD Pipelines, Blockchain Wallets, SEO Tools, Maps, Performance, Peer-to-peer Networking, Web Development, Ethereum Open Source, Ethereum Virtual Machine (EVM), Artificial Intelligence (AI), Deno, Natural Language Processing (NLP), Large Language Models (LLMs)
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
Share your needs
Choose your talent
Start your risk-free talent trial
Top talent is in high demand.
Start hiring