Olaoluwa O. Full-Stack & Mobile Application Developer ⭐ 5.0 💲**$75.00/hr** 💼 20+ Projects I specialize in designing and developing high-performance web and mobile applications that help businesses scale, streamline operations, and deliver exceptional user experiences. From MVPs to production-ready platforms, I build secure, scalable, and maintainable solutions tailored to your business goals. Whether you’re launching a startup, modernizing an existing product, or building a cross-platform mobile application, I provide end-to-end development with a strong emphasis on quality, performance, and long-term maintainability. Core Expertise • Full-stack development with React, Next.js, Node.js, NestJS, Express.js, PostgreSQL, and TypeScript • Cross-platform mobile application development using React Native and Expo for Android and iOS • REST API architecture, authentication systems, payment gateway integrations, and cloud deployment • Responsive, modern UI/UX implementation with performance optimization and clean, scalable code • Full product development lifecycle—from planning and architecture to deployment, testing, and ongoing maintenance • Clear communication, reliable delivery, and long-term technical support I take pride in building software that is not only visually polished but also robust, scalable, and engineered for real-world use.

I am a highly experienced full stack and devops engineer that can bring valuable expertise to a variety of projects; Whether you are a small business looking to launch an ecommerce website, a nonprofit looking to modernize your digital infrastructure or an entrepreneur looking to stand up a computational prototype, I'm your guy! I've founded a profitable business and have a range of expertise not only in hard technical areas, but also adjacent domains like digital marketing/SEO, customer discovery and UX design. If you're looking for someone pragmatic, who possesses broad experience, excellent interpersonal skills and who can delivery quickly and reliably, then you should shoot me a message!

I am a full-time full-stack developer with 7+ years of experience. I have worked on Angular, React, Ionic and Node for businesses worldwide. My main focus is to deliver you quality products. I know how to deliver projects on time. I have completed dozens of projects off to the Upwork with various software development companies worldwide, which made me well adapted to working with start-ups and big-sized companies. I have just started my journey in Upwork and looking for a positive response. Thanks for your time and consideration. I am looking forward to working with you. Feel free to contact me or schedule an interview. My Frontend skills: ✔️ Angular | AngularJS | NgRx | RxJS ✔️ React.js | React Native ✔️ JavaScript | ES 6+ ✔️ TypeScript ✔️ jQuery ✔️ HTML 5 | CSS3 | Sass | Less | Tailwind | Bootstrap Backend skills: ✔️ Node.js | Express ✔️ .Net Core | ASP.NET | C# ✔️ REST | SOAP ✔️ WebSocket | Socket.IO ✔️ Google cloud APIs integration for Translate, text to speed, Maps, etc. Database / Storage: ✔️ RDS: PostgreSQL | MySQL | MS SQL | Oracle | Amazon RDS | Google Cloud RDS ✔️ NoSQL: Firestore | Firebase Realtime | MongoDB | DynamoDB ✔️ Redis Cloud and DevOps Skills: ✔️ AWS S3 | EC2 | Lambda | Google cloud functions | Google cloud store ✔️ Docker | Kubernetes | GCP GKS | AWS EKS ✔️ Nginx | IIS | Apache ✔️ PM2 ✔️ AWS | GCP | Azure | Digital Ocean | IBM Cloud | Oracle cloud (certified) Management Tools : ✔️ Agile | Scrum ✔️ GitHub | GitLab | Bitbucket | AWS Code Pipeline | Azure DevOps ✔️ Asana | Trello | Jira | Teams WHAT CAN I DO FOR YOU? 📌 I can analyze, design, lead, develop and implement enterprise applications. 📌 I can develop complex, large-scale, and low-latency enterprise projects. 📌 I can Analyse and optimize your website performance 📌 I can Develop API for mobile applications 📌 I can do API Integrations in your existing backend 📌 I can help you set up hosting, setup IAM rights in the Cloud, and setup up Cloud monitoring tools I CAN ENSURE: ✔️ Fast response and good communication skills ✔️ Hand-coded, W3C valid and well organized commented code ✔️ Testing and cross-browser / cross-device compatibility ✔️ SEO friendly, table-less mark-up and speed optimized frontend ✔️ 100% refund if not satisfied within 30 days Once again, thanks for your time and consideration.

I build AI systems that actually run in production, not just demos. Most clients come to me after hitting the same issues: RAG not accurate, agents unreliable, or AI pipelines that don’t scale. That’s where I step in. I’m a Senior ML and LLM Engineer (10+ years), recently working at NexGen Cloud and Holi GmbH, where I built: ☑️Enterprise AI platforms serving 100+ clients with 99.9% uptime ☑️RAG systems (multimodal, hybrid search, real-time pipelines) ☑️AI agents connected to APIs, tools, and business workflows ☑️High-performance inference systems (sub-200ms latency, cost reduced ~40%) What I can help you with: ☑️RAG Systems (LLM + Data) PDFs, databases, internal tools → accurate retrieval (LangChain, LangGraph, pgvector, Pinecone) ☑️AI Agents & Automation Multi-step workflows, tool calling, OpenClaw-style systems ☑️LLM Systems (Production Ready) OpenAI, Claude, Gemini, structured outputs, evaluation, guardrails ☑️Backend + APIs FastAPI, Django, Node, async pipelines, Redis, scalable systems ☑️Search & Recommendations Hybrid search (BM25 + vector), ranking, personalization I’ve built systems handling 1000+ ML jobs/month and real traffic I focus on accuracy + reliability, not just “AI output” I design systems your team can actually maintain 𝐐𝐮𝐢𝐜𝐤 𝐰𝐢𝐧𝐬 𝐈’𝐯𝐞 𝐝𝐞𝐥𝐢𝐯𝐞𝐫𝐞𝐝 Improved search latency and relevance by 40% Increased recommendation quality by 35% Reduced AI infrastructure cost by up to 70% If you’re building something serious with AI and want it done properly, 𝐥𝐞𝐭’𝐬 𝐭𝐚𝐥𝐤.

My name is Darko Nikolic I am programmer with 7 year of experience in game development. I have worked on games for multiple platforms(Windows, Mac, Android and IOS) both 2D and 3D games.

My name is Jeff Tillett. Please allow me to tell you a bit more about my experience and skills. I have worked with computers and Internet technologies for over 20 years I am a survivor of the Internet boom and bust. During that time, I assisted many startups in successfully building business and e-commerce ventures. As a developer for a distance-learning Internet start-up, my team and I crafted a custom LMS and all of the interactive and media content that went in it. Since the success of that project, I have mostly focused on learning design. I worked for various companies as an interactive developer and Instructional Designer, including Adobe, T-Mobile USA, Microsoft, Entirenet, Float Mobile Learning, Apple, and Amazon. I help organizations leverage AI to create video, interactive media, and mobile technology to create high-performance, engaging learning.

PROFESSIONAL SUMMARY Quality-focused Senior Software Engineer with 10+ years of experience designing, developing, integrating, testing, and modernizing enterprise applications supporting government organizations and mission-critical operations. Hands-on experience using Playwright for ASP.NET Core and web end-to-end testing and Appium for mobile end-to-end testing. Strong background in C#, .NET 8, ASP.NET Core, REST APIs, SQL Server, React, TypeScript, Azure, AWS, Agile delivery, and CI/CD. Experienced translating requirements into testable solutions, collaborating with cross-functional teams, investigating defects and root causes, documenting technical processes, and improving delivery workflows. Eligible to obtain and maintain a Public Trust clearance. CORE SKILLS Test Automation & Quality: Playwright; Appium; Visual Studio; Azure DevOps Boards; Azure Test Plans; end-to-end; regression; API; integration; smoke; user-acceptance; accessibility and Section 508 testing;

With 5+ years of full-stack software development and deep expertise in LLM orchestration/agentic pipelines, I bridge the gap between frontier models capabilities and production-grade applications. Whether you need a launch-ready MVP or an enterprise-level cross-platform app, I build software that is robust, user-centric, and built to monetize. What I can help you build: -AI & Agentic Orchestration: Custom LLM pipelines, Autonomous Agentic Loops, Harness Engineering, Evals, Secure Ephemeral Sandboxes/Long Running Processes, RAG, and MoE routing integrated directly into your product. -Full-Stack Web Applications: High-performance, SEO-optimized web platforms optimized for conversions and robustness. -Cross-Platform Mobile Apps: Native-feel iOS and Android applications built for high retention and scale. -Scalable Infrastructure: Multi-stage CI/CD pipelines, and multi-platform cloud deployments (AWS, GCP, Vercel). -Testing & Quality Assurance: Comprehensive test suites (unit, integration, E2E) baked into the development pipeline. -Other: Complete payment system setup (Stripe/Mollie/MangoPay), secure authentication and cloud databases/distribution. My stack: -AI & ML: Python, Custom LLM Orchestration, Langchain, Firecracker VMs/E2B, OpenAI/Anthropic/Deepseek/Z.AI/Kimi... APIs, Vector Databases -Frontend & Mobile: Next.js, React, React Native / Expo, Tailwind CSS, TypeScript, Zod, Zustand -Backend & Cloud: Node.js, Python, Supabase, MongoDB, PostgreSQL, Serverless, Redis, S3/Cloudfront -DevOps & Infrastructure: Docker, Kubernetes, GitHub Actions, Sentry, AWS, GCP, Vercel, Nginx, Helm, Cloudflare -Testing & QA: Jest, Vitest, Playwright, Pytest, React Native Testing Library, Unit / Integration / E2E Automated Suites If you need a reliable developer who can dive into an existing repo, establish proper CI/CD and testing, or architect a complex AI product from scratch, reach out below.

I help founders and operators turn a problem into shipped software - I own the what-to-build, not just the code. An AI-native pipeline lets me deliver in weeks what agencies quote in months: AI does the volume, my judgment owns the architecture, the quality, and whether it's the right thing to build. Fifteen years as a SaaS founder and product manager (marketing tech, fintech), now running production delivery on Claude Code. I act as a product partner - scoping, shaping, and building - not a task-taker. WHAT I DO - 0-to-1 platforms, full-stack web and mobile - Legacy modernization (PHP and classic .NET to React) - AI agents and production MCP servers that wrap your existing systems - Workflow automation that turns manual processes into software SELECTED WORK - Access Infinity (pharma market access) - 0-to-1 platform now used by major pharma brands, delivered around $20K vs a $50K quote, in half the timeline - Alma Tire (commercial truck parts) - parts-search platform aggregating 9 vendor catalogs, ~15% cost savings - Prompt PR - Campaign Impact Tracker tracing campaign ripple across social and news, in half a competing agency's time - MethodRevenue (B2B agency) - analytics automation: 10 hours per client down to 20 minutes - Strategic Wealth Partners - client reporting automation: 1 hour per client down to 10 minutes - Free Will Lawyer (estate planning) - document generator: 45 minutes per document down to 10 - Kosher Dynamics - legacy PHP portal rebuilt in React: 22 admin modules + 12 inspector features HOW I WORK Structured product thinking up front (what's worth building, what to cut), then an AI-native build pipeline - architecture review, automated browser QA, and multi-model code review on every change. Senior-quality software, shipped in weeks. Based in New York City. Let's talk about what you're trying to ship.

I help businesses replace spreadsheets, outdated software, and manual processes with secure, modern custom applications. With more than 26 years of experience in software development and technology consulting, I design and build custom business software that improves efficiency, automates workflows, and gives organizations the tools they need to grow. Whether you’re starting with an idea, replacing a legacy system, or expanding an existing application, I can help turn your vision into a reliable, scalable solution. My primary expertise includes: * Custom Web Application Development * SaaS Application Development * Business Management Systems (CRM, ERP, HR, Scheduling, Billing) * Customer & Employee Portals * Workflow Automation * Payment Processing & Stripe Integrations * REST API Development & Third-Party Integrations * Database Design & Optimization * Legacy System Modernization * Cloud-Based Applications Technical Skills: * Angular * TypeScript * JavaScript * Node.js * Express * Parse Server * PostgreSQL * MySQL * SQL Server * REST APIs * Stripe * Docker * Git/GitHub * AWS * Microsoft Azure As President of SR2 Solutions, I’ve led software projects for businesses of all sizes, delivering solutions that are practical, maintainable, and built for long-term success. I combine strong technical skills with a deep understanding of business operations, allowing me to communicate effectively with both technical and non-technical stakeholders. One of my biggest differentiators is my cybersecurity background. With over 26 years of experience in information security and risk management, I develop software with security built in from day one. Authentication, authorization, secure APIs, data protection, and industry best practices are part of every project—not afterthoughts. Clients appreciate my clear communication, attention to detail, and commitment to delivering high-quality work on time. My goal isn’t simply to write code—it’s to build software that solves real business problems and provides lasting value. If you’re looking for a dependable developer who can take a project from concept to deployment while keeping security, scalability, and maintainability in mind, I’d love to discuss your project.