I'm a Ruby on Rails developer and full stack developer focused on SaaS and FinTech products. Day to day that's Ruby on Rails and React.js (Next.js, TypeScript) on PostgreSQL, deployed on AWS with Docker when the app needs it. 6+ years building production web applications — Top Rated Plus, 100% Job Success, 6,100+ Upwork hours, 85+ jobs. Most contracts run 1–4 years on one codebase. Available 30+ hours a week. Two years at SmartZip on their Rails + React lead-gen SaaS. Since then: B2B SaaS features, Stripe billing, GraphQL and REST APIs, Elasticsearch for search, Heroku-to-AWS migrations, Rails version upgrades. Frontend is React and Next.js; backend is Rails, Sidekiq, RSpec, and PostgreSQL done properly. I've also been adding AI features to live products — LLM API integration, chat interfaces and workflow automation. A long-term client, Olivier: "30+ eLearning apps, nearly 4 million plays — proactive, doesn't need hand-holding." Hiring a Ruby on Rails developer for ongoing SaaS work, full stack Rails + React, FinTech/Stripe, or a legacy app that needs a Rails upgrade or cloud migration? Send your repo or roadmap, I'll reply with an honest take on fit.

Full Stack Java Engineer with 5+ years of experience building scalable, production-grade systems for logistics, food delivery, and enterprise platforms. I specialize in Spring Boot microservices architecture and AI-powered backend systems — designing end-to-end solutions that handle high traffic, complex workflows, and real-time data processing. My background in logistics technology means I understand not just the code, but the business operations behind it. What I bring to your project: - AI integration using OpenAI, Gemini, and LangChain4j for intelligent automation and chatbot backends - Microservices architecture with Spring Boot and Spring Cloud - Event-driven systems using Apache Kafka and RabbitMQ - Full stack development with React.js and Vue.js frontends - REST API design, development, and third-party integrations - AWS infrastructure — EC2, RDS, S3, deployment pipelines - Database design and optimization across MySQL, PostgreSQL, and Oracle - JWT-based authentication and Spring Security - Legacy system migrations and monolith-to-microservices transitions - Docker, CI/CD pipelines, and production deployment I have built and maintained systems processing hundreds of thousands of records daily — including a 2.5-year long-term engagement delivering a full-stack logistics and food delivery platform on AWS, earning a 5.0 rating across every review. I do not disappear after handing over code. I ask the right questions before starting, communicate clearly throughout, and flag issues before they become problems. Clients who work with me once tend to come back. 100% Job Success Score across every contract on Upwork. If you need a reliable full-stack engineer who builds intelligent, scalable systems — let's talk.

Hello! I am Hamayun, a Node.js and NestJS backend developer specializing in scalable APIs, SaaS platforms, and blockchain-powered applications built with NestJS, PostgreSQL, and TypeScript. With 6+ years of backend experience, I help startups and product teams ship production-ready systems that perform under real-world load. Clean architecture, no shortcuts. What I build: ✅ REST & GraphQL APIs with authentication, RBAC, and third-party integrations ✅ SaaS backends with multi-tenancy, subscription billing (Stripe), and user management ✅ Blockchain and Web3 backends with token systems, smart contract integrations, and transaction pipelines ✅ Real-time features using WebSockets and event-driven architecture ✅ Database design and query optimization with PostgreSQL and TypeORM ✅ Cloud deployments on AWS with Docker and CI/CD pipelines Recent projects I've built backends for: ✅ Refecoin. com: A blockchain platform for synthetic real estate token trading ✅ Tournated. com: An all-in-one sports management SaaS used by federations and clubs globally ✅ Servita. com: An AI-powered digital transformation platform serving enterprise clients My preferred tech stack: Node.js · NestJS · PostgreSQL · TypeScript · GraphQL · Redis · AWS · Docker · Stripe The approach is simple: build systems that are stable, fast, and easy to extend as the product grows. If you're working on something where backend performance, structure, or scalability actually matters, feel free to share the details.

About Us = = = = At ALGO, we design and develop systems, platforms, and automation powered by AI and emerging technologies. We integrate AI agents, software, data, and infrastructure to turn complex use cases into real, scalable, production-ready solutions. What We Do = = = = We build solutions in: AI, agents, platforms, systems, and automation, along with Blockchain, IoT, Immersive Technologies, Robotics, Game Development, Cybersecurity, Digital Twins, and Quant Engineering. Our focus is clear: moving from isolated experiments to integrated systems that generate real business impact. Why ALGO = = = = ALGO combines advanced engineering, expertise in emerging technologies, and strong execution capabilities to help companies design, develop, and scale complex technology solutions. Let’s build what matters = = = = If you’re looking to turn AI or emerging technologies into real solutions, ALGO can help.

Full-stack developer with 6+ years building production web apps for SaaS startups and e-commerce businesses. I specialize in Next.js, React, Node.js, FASTAPI and PostgreSQL the stack most modern web products actually run on. Clients usually come to me with one of three problems: - They have a SaaS idea and need the full build auth, dashboards, Stripe billing, multi-tenancy, and deployment. - They run an online store that's slow or hard to manage, and want a faster, headless alternative with a proper CMS. - They have an existing app that's buggy, slow, or needs new features added without breaking what already works. Recent work (live and in production): - Billboard advertising marketplace location search, filters, and a full booking flow. Built for a real business and currently in use. - Multi-tenant SaaS dashboard with isolated workspaces, role-based access, and usage analytics. - Headless e-commerce store with Stripe checkout and a CMS so the client manages products without touching code. - CMS-powered marketing site with sub-second load times and a no-code editing workflow for the client's team. Core stack: Next.js · React · TypeScript · Tailwind CSS · Node.js · NestJS · FastAPI · PostgreSQL · Prisma · MongoDB · Stripe · Sanity CMS · NextAuth · Supabase · AWS · Vercel · Docker How I work: - Clear written communication daily or twice-weekly updates, your pick. - Available in US-compatible hours (overlap with EST/PST). - Clean, documented code another developer can pick up without calling me. If you're building something new or fixing something that's already live, tell me: what's the outcome you need, and what's the rough timeline? Happy to jump on a quick call to scope it out.

Seasoned technology professional with 20+ years of comprehensive expertise in Linux systems, SQL databases, Perl programming, and data transformation and analysis. Proven ability to write, optimize and troubleshoot complex SQL queries.

900+ hours on Upwork, 100% Job Success, Top Rated, Python backend developer who ships FastAPI and PostgreSQL services that actually hold up in production. I work with founders and small teams who want clean, tested code they can extend later, not throwaway scripts that need rewriting in six months. CORE SERVICES → FastAPI backends with PostgreSQL, async, Pydantic, Alembic, transactional safety → Automation scripts and API integrations, payments, scraping, scheduled jobs → Desktop apps in PyQt, Tkinter, Streamlit, Electron → Backend audits, code reviews, refactors, debugging existing systems → Full-stack add-ons with React and Tailwind when needed HOW I WORK Clean code, tests first, type hints, small functions, named clearly. SOLID and CD as practice, not buzzwords. I tell you when a request is going to cost more than it should, and I do not disappear mid-contract. Send a message with what you are building or what is broken, and I will tell you honestly whether I am the right fit.

Hands on Data architect & Lead data engineer, with 12+ years of experience in designing & building end to end high velocity, high volume peta byte real time & batch data platforms from scratch on clouds & on-prem. Kubernetes native development from the beginnig. I develop distributed & scalable back-end systems using using languages like goLang, Rust & python. Lately Started working on integration of AI, RAG, MCP Servers & MLops Platforms into data platforms. Developed self hosted llms applications using Ollama and llm observability using langfuse. Mordenize existing data platforms with AI first approach. Hybrid semantic mapping layers or unstructured and structured data using heuristics, memory and LLMs. Built & worked on peta byte scale streaming, batch data & AI platforms in top companies. An open source contributor to data technologies & products like Airbyte etc. Love working on database internals, performance and optimizations. I have experience working with telemetry data, payments data, video data, sports data, eCommerce data & affiliate marketing data, logs data, clickstream data. Skill Set: Big Data Technologies: Spark, Kafka, Flink, Presto, Dremio, Hudi, Deltalake Data warehouses: Snowflake, Druid, Clickhouse, Redshift, SingleStore(Memsql), Quest Databases: Postgres, Mysql, Cassandra, DynamoDB, DuckDB Programming languages: Golang, Python, Rust, Scala, Java Visualization: Tableau, Apache Superset, Zoomdata Data Technologies - Airbyte, Fivetran, Dagster, Airflow, Nifi, Kubeflow, ElasticSearch, OpenSearch Platforms: Databricks, Snowflake, Cloudera, Supabase, Aiven Ops: Kubernetes, Docker Cloud: AWS, GCP, Azure

⚡ Odoo Expert helping startups go from messy spreadsheets to a clean, working ERP — fast. Top Rated | 15+ years | Custom Modules · Migrations · Full Implementations If you're a growing business drowning in manual processes, I help you implement Odoo so your team actually uses it — without the chaos of a typical ERP rollout. What I do: ✅ Custom Odoo module development (Python, OWL, XML) ✅ Odoo 19 implementation from scratch ✅ Migration from older Odoo versions or other ERPs ✅ Project management for Odoo rollouts (Agile/Scrum) ✅ Ongoing support, bug fixes & performance tuning Industries I've worked with: Manufacturing, Retail, Services, Logistics Why clients choose me: → I scope clearly before I build — no surprise costs → I write clean, documented code your team can maintain → I stay until it works, not just until it's "delivered" Let's talk about your Odoo project. Message me and I'll reply within a few hours.

Hi, I’m Dennis Kimani — a Full-Stack Developer with a strong focus on building fast, secure, and scalable web applications. I specialize in designing and developing robust backends using Python (Flask & Django) and creating clean, responsive frontends with React. Core Skills: 🐍 Python, Flask, Django ⚛️ React, JavaScript, HTML, CSS 🔗 RESTful APIs & JSON Integration 🧩 PostgreSQL & MySQL 🔐 JWT Authentication & Role-Based Access 🚀 Docker, Git, CI/CD, and Deployment Projects I’ve Built: ✅ ISP Management System – full backend with user/customer management, billing, analytics, and dashboards. ✅ Event Management Platform – user authentication, event creation, and real-time event tracking dashboards. What You Can Expect: ✨ Clean, maintainable, and scalable code 💬 Clear communication & timely progress updates 🧠 Strong problem-solving and attention to detail 🤝 Professional collaboration from start to delivery 🔹 Verified Upwork Freelancer 🔹 Currently working on a backend contract 🔹 Open to long-term or short-term remote projects Let’s build something impactful together — feel free to reach out anytime!