Babafemi A.

Need a mobile MVP shipped, an app rescued, or releases that don't take half a day? I'm a Chicago-based senior engineer (8+ years) building with React Native and Flutter for mobile, and Next.js for web. Since my last Upwork contract in 2023, I've worked in React Native as Mobile Application Developer at Rhaeos (2023–2024) and Senior Software Engineer at Telus Digital, formerly WillowTree (2024–2026). My Upwork reviews come from the Flutter work before that. What clients said here on Upwork (5.0-star reviews): "Codes and communicate very well. Get things done in a timely manner" "Will work again. Great work and easy to collaborate with" Two mobile lanes and one web lane: • React Native (iOS & Android): new apps, rescues, design systems and release pipelines, in TypeScript, with Expo when it fits. • Flutter (iOS & Android): new apps and MVPs in Dart, with push notifications, automated tests, crash reporting, analytics and Fastlane CI. My 8 Upwork jobs (2021–2023) were mostly Flutter, including an MVP, and every review above comes from that work. • Next.js (web): responsive, accessible React and Next.js apps, plus the Node.js or GraphQL API behind them. Recent results: • Cut iOS release time from about 5 hours to about 40 minutes by automating builds, code signing, and TestFlight and Intune distribution with Fastlane and Azure DevOps. • Built a React Native design system adopted by 10 engineering teams and 10+ production apps: Figma designs turned into tokenized, light/dark-themed, accessible, i18n-ready components, tested in Storybook. The result: fewer UI bugs and faster delivery. • Reduced incident triage time from about 2 hours to under 30 minutes with Grafana and Azure Application Insights dashboards. • Built the React Native chat client and source-citation viewer for a RAG audit assistant designed for 5,000+ clinical research associates. Its users reported verification dropping from hours to under 2 minutes per 1,000+ page manual. • At Rhaeos (1-year contract), improved the patient app and built the clinician (CRA) app for an FDA Breakthrough Device-designated hydrocephalus shunt monitor (designation granted in 2020), kept both within FDA and HIPAA requirements, and built their AWS data pipeline and Cognito auth from zero, plus a Swift module for Bluetooth LE Secure Connections. • At Eminent Technology (2019–2023): web and mobile apps across 7+ enterprise engagements for organizations including ExxonMobil, Pool Corp. and Oceaneering, and a React Native telemedicine platform serving 10,000+ users. What I can do for you: • Mobile MVPs in React Native or Flutter: from Figma to TestFlight and Google Play, with sign-in (Firebase Auth, Cognito) and Stripe payments, on a codebase your next hire can read. • App rescue and performance: I find out why the app is slow, crashing or losing data (Sentry, Xcode Instruments, Hermes), fix the cause, and add tests so it stays fixed. • Release & CI/CD for iOS and Android: Fastlane, Gradle, Expo EAS, GitHub Actions and Azure DevOps. Automated builds and code signing, separate dev/staging/production builds, and TestFlight, Intune and Google Play releases. • Native modules & hardware: Swift native modules, Bluetooth Low Energy, real-time telemetry and biometric authentication. • Offline-first & secure apps: encrypted SQLite storage that survives network drops, and role-based access. • Design systems: tokenized, themed, accessible component libraries in Storybook, shared through a monorepo or an npm package. • Next.js web apps: React and Next.js front ends with Tailwind CSS and Redux, checked with Lighthouse. • Long-term contracts: I own your mobile or web front end, with code reviews and written architecture docs. Tech stack: Languages: TypeScript, JavaScript, Dart, Python, SQL; Swift for native modules Mobile: React Native, Expo (EAS), Flutter, Zustand, Redux, TanStack Query, MobX, SQLite Web: React, Next.js, Tailwind CSS, Storybook, Angular, Vue.js Backend & Cloud: Node.js, Express, GraphQL, Firebase, AWS (Lambda, S3, Cognito), Azure, PostgreSQL, Docker, Kubernetes Testing: Jest, React Native Testing Library, Detox, Maestro, Playwright How I work: clear communication, regular progress updates, and clean, well-tested code your team can maintain after I hand it off. Before I write any code, you get a written plan with scope and either an hourly estimate or fixed-price milestones. At handoff, you get a knowledge-transfer session. I'm available for more than 30 hours a week, on US Central Time, and a US Permanent Resident. Past clients endorsed me as a Clear Communicator, Reliable, Committed to Quality and Collaborative. Have an app to build, fix, or scale? Send me a short description of your project, and I'll reply with next steps within 24 hours. Not sure of the scope yet? Start with a short paid discovery: you get a written spec, a screen list and fixed-price milestones before you commit to a build.