Joseph Okolo

Fintech company building Celler — a B2B platform for buying and selling cryptocurrency and fiat. Backend: Led full rewrite of Celler V2, migrating the entire product from Laravel (V1) to NestJS and PostgreSQL. Designed scalable backend architecture for a multi-sided crypto/fiat marketplace with B2B transaction flows. Built secure APIs supporting user onboarding, order management, and fiat-crypto exchange.

Implemented role-based access control, secure authentication, and performance-optimised database queries. Fullstack: Integrated backend APIs into the React/Next.js frontend using TanStack Query for server state management. Fine-tuned UI logic and ensured end-to-end data flow between backend services and the client interface. Collaborated closely with the frontend to validate API contracts and resolve integration issues in production.

Fintech company building investment and wealth products, including Rebble and Bloomvest. Backend: Hired as Engineering Lead for Bloomvest, responsible for backend architecture and delivery. Led the launch of Bloomvest V2, overseeing major system upgrades and production rollout.

Migrated core product data from a legacy SQL database to PostgreSQL, improving data integrity and scalability. Refactored backend codebase from plain Express.js to NestJS, introducing modular architecture and dependency injection. Designed scalable APIs supporting investment flows, user portfolios, and financial transactions.

Fullstack: Implemented backend APIs directly into the React/Next.js frontend using TanStack Query for efficient data fetching and caching. Fine-tuned UI logic, ensuring smooth integration between backend services and the client layer. Worked closely with product and frontend teams to ship stable releases and improve system reliability.

Development studio contracting backend engineers to build products for external clients. Contracted as backend developer responsible for delivering full backend systems for client projects. Built 2 production-ready projects using NestJS, Express.js, MySQL, Prisma, and PostgreSQL. Designed and delivered scalable backend architectures from scratch tailored to individual client requirements.

Built Trilla — a real estate investment platform with fractional ownership, AI-powered assistance, and fiat/crypto payments. Developed TriPay — a global QR/NFC-based scan-to-pay gateway enabling fiat-crypto interoperability, featuring wallets, FX engine, and merchant APIs.

Designed secure multi-role backend architectures (Users, Wallets, Transactions, Agents, Admins) with NestJS & MongoDB/Supabase. Architected real-time features for messaging, booking, and payments, ensuring high performance and security.

Blockchain product studio contracted to build DeFi and Web3 products for external clients. Implemented blockchain APIs and integrated Ethers.js and Web3.js SDKs across multiple DeFi products: Curvance, Mozaic, Pike, and The Rollup. Built and deployed smart contract integrations — reading contract state, listening to on-chain events, and triggering transactions from the backend.

Architected and built a high-performance blockchain indexer for Curvance, enabling faster and more reliable on-chain data retrieval for the dApp. Built secure backend for The Rollup with email/MetaMask authentication and GraphQL endpoints using Clerk. Created the Studio Attendance Bot in Go, streamlining team attendance tracking.

Addressed bugs and user-reported issues in DappLabs products including the Airdrop Checker. Enhanced application stability and maintained high standards for security and performance.

Built NFT minting pages, NFT marketplaces, decentralised exchanges (DEXs), trading bots, and mini Telegram apps. Delivered custom solutions including Web3 lottery apps, e-commerce APIs, and blogging platforms.

Collected, cleaned, and analysed structured datasets using Microsoft Excel and SQL to support business decision-making. Built pivot tables, dashboards, and data summaries to surface trends and insights for internal stakeholders.

Wrote SQL queries against relational databases to extract, join, and cross-reference operational data. Collaborated with senior analysts to prepare weekly and monthly performance reports for management.