Hi, I’m Zlata. I’m basically a typical American software developer... just living in Ukraine now. And I always work in the EST timezone. I’ll write everything in any tech stack you have 😄 I’m a Software Engineer with 8+ years of experience as a Ruby on Rails developer, React developer, Node.js developer, Python developer, and .NET developer. I work with Ruby on Rails, React, Node.js, Python, .NET, PostgreSQL, Docker, AWS, JavaScript, TypeScript, API development, API integration, and SaaS software development. I help companies build and improve SaaS platforms, ERP systems, CRM tools, dashboards, marketplaces, internal systems, API products, and complex web applications using Ruby on Rails, React, Node.js, Python, and .NET. My focus is clean product logic, stable delivery, scalable architecture, and software that stays easy to maintain as the business grows. 📊 My Achievements in Numbers: 🔶 Ruby on Rails Developer for a Construction Application Platform ▪ Helped build a Ruby on Rails + React platform for managing construction applications, reviews, documents, and stakeholder workflows. ▪ Reduced application review time by 42%. ▪ Supported 18,500+ construction applications processed in the first year. ▪ Helped the product reach $1.4M ARR within 14 months. ▪ Worked with Ruby on Rails, React, PostgreSQL, Docker, AWS, S3, and API integration. 🔶 React Developer for a Construction Materials ERP SaaS ▪ Helped improve a complex ERP SaaS platform for concrete, aggregates, and asphalt producers. ▪ Improved sales, pricing, and operational workflows through better product logic and scalable software architecture. ▪ 98% of demo users became clients after product improvements. ▪ 91% of users rated the interface as clear and intuitive. ▪ The product later raised $3.4M. ▪ Focused on React, Ruby on Rails, SaaS workflows, API development, and complex web application structure. 🔶 Node.js Developer for an Aviation Maintenance SaaS ▪ Helped improve a complex aviation maintenance SaaS product used by field teams. ▪ 96% of demo users became clients after the product improvements. ▪ 97% of field users adopted the product after the first try. ▪ Reduced user errors by 41% and made onboarding 62% faster. ▪ Supported product logic, API integration, dashboards, and connected SaaS workflows using Node.js, React, Ruby on Rails, and API development. 🔶 Python Developer for an AI Healthcare SaaS ▪ Supported an AI-powered healthcare platform that grew from a chatbot into multiple AI agents for clinics and hospitals. ▪ The product raised $20M+. ▪ Helped support workflows that increased patient visits by 31%. ▪ Helped reduce call abandonment by 98%. ▪ Worked with Python, API integration, automation workflows, AI-related product logic, and scalable SaaS architecture. 🔶 .NET Developer for a Utility Billing Platform ▪ Helped improve utility billing workflows for a SaaS platform processing complex customer, billing, and reporting data. ▪ Helped process $14M+ in utility bills within 6 months. ▪ Reduced billing cycle time from 9 days to 1.5 days. ▪ Supported 96% client retention through better product stability and workflow clarity. ▪ Worked with .NET, React, API development, reporting logic, SaaS architecture, and reliable software delivery. Why should you hire me as a Software Engineer? ▪ 8+ years of experience with Ruby on Rails, React, Node.js, Python, .NET, JavaScript, TypeScript, PostgreSQL, API development, API integration, and SaaS software development. ▪ 120+ successful projects delivered across B2B SaaS, ERP, CRM, healthcare, construction, logistics, fintech, aviation, and internal business platforms. ▪ Strong experience with Ruby on Rails, React, Node.js, Python, and .NET for SaaS products, dashboards, admin panels, API-first platforms, integrations, automation, AI features, and enterprise systems. ▪ I use Claude, Cursor, GitHub Copilot, and ChatGPT to speed up research, debugging, refactoring, and delivery. ▪ I work well with founders, CTOs, product managers, and teams that need clear communication across Ruby on Rails, React, Node.js, Python, and .NET products. What I can help you with: ✔️ Build or improve Ruby on Rails SaaS products ✔️ Create React dashboards, portals, admin panels, and SaaS interfaces ✔️ Build Node.js services and API integrations ✔️ Support Python automation, data workflows, and product logic ✔️ Work with .NET systems and connected software platforms ✔️ Build API-first products with Ruby on Rails, React, Node.js, Python, .NET, PostgreSQL, Docker, and AWS ✔️ Improve performance, stability, and maintainability of existing Ruby on Rails, React, Node.js, Python, and .NET applications ✔️ Support SaaS, ERP, CRM, fintech, healthcare, logistics, construction, and internal tools Need help with Ruby on Rails, React, Node.js, Python, .NET, API development, or SaaS development? Message me and let’s discuss your product. 📩🤝

I build AI-powered web applications and full-stack systems that are fast, scalable, and built to last. With 10+ years of experience, I work with founders, startups, and product teams to ship software that actually solves problems - from early MVPs to production-grade platforms. What makes me different: I combine deep full-stack engineering (Ruby on Rails, React.js, Node.js) with modern AI/ML capabilities (RAG pipelines, LLM integrations, AI agents) - so I can take your product from idea to a working, intelligent system. ━━━━━━━━━━━━━━━━━━━━━━━━━━ 🤖 AI & Automation ━━━━━━━━━━━━━━━━━━━━━━━━━━ ▪ RAG pipelines (LangChain, LlamaIndex, vector DBs) ▪ LLM integrations (OpenAI, Anthropic, Gemini) ▪ AI agents & workflow automation ▪ Chatbots, document Q&A, intelligent search ▪ n8n, Make, Zapier automation flows ━━━━━━━━━━━━━━━━━━━━━━━━━━ 💻 Full Stack Development ━━━━━━━━━━━━━━━━━━━━━━━━━━ ▪ Ruby on Rails (expert-level, 10+ years) ▪ React.js, Next.js, Node.js, Express ▪ PostgreSQL, MySQL, MongoDB ▪ REST APIs & third-party integrations ▪ SaaS platforms, dashboards, CRMs, marketplaces ━━━━━━━━━━━━━━━━━━━━━━━━━━ 🚀 What I bring to your project ━━━━━━━━━━━━━━━━━━━━━━━━━━ ▪ Led engineering teams & owned technical decisions ▪ Built and scaled SaaS products end-to-end ▪ Refactored legacy codebases into clean systems ▪ Clear communication + reliable delivery ▪ I treat your product like my own If you're building something ambitious - whether it's an AI-powered SaaS, a high-traffic web app, or an automation system - let's talk. 📩 Send me a message and you'll expect the reply promptly.

I am a full-stack Ruby on Rails developer with years of experience and a degree in computer science. I appreciate clean, beautiful codes & clear communication. I am experienced with building, maintaining, and scaling web projects using Ruby on Rails. I have done everything from the most basic CSS to setting up production servers. I have been exposed to different industries using various processes and technologies. I'm also a skilled and passionate Shopify developer with more than 6 years of experience in crafting exceptional and seamless e-commerce solutions. My journey into the world of web development started with a love for creativity and problem-solving, which eventually led me to specialize in Shopify development. SKILLS and KNOWLEDGE: # Web Development - Expertise in developing, profiling, and debugging with Rails and Ruby - Experience in designing REST-APIs and profiling Rails applications. - Engineering experience with building scalable MVC, event-based, modular, API-driven software. - Experience in CMS gems (Refinery, ComfortableMexicanSofa), - Strong knowledge of HTTP, REST, Redis, PostgreSQL, MySQL, MongoDB - In-depth knowledge and practice in TDD with Rspec, Cucumber. - Strong knowledge about popular gems such as Devise, Cancancan, Rolify, Paperclip, Trailblazer, etc... - Working knowledge of Capistrano, Mina, Git. - Front end HTML, JS, CSS ability. - Familiar with ReactJS, VueJS, Jquery, CoffeeScript, AngularJS, BackboneJS, ExtJS, Twitter Bootstrap, Foundation. - Experience in using/setting up continuous Integration tools such as Codeship, Jenkins, Tddium. - Working knowledge in Google API, Facebook API, Stripe API, Paypal API. - Web administration experience in Linux/Windows base servers. SSH, Cpanel, Amazon Web Service - Working experience in Agile environment. - Cloud experience​ in Amazon, Engie Yard, Digital Ocean. # Shopify skills: - Shopify Expertise: In-depth knowledge of Shopify's platform and features. - Custom Theme Development: Crafting captivating and unique online store designs. - Shopify App Development: build apps to add advanced features to stores. - Liquid Templating: Creating dynamic and personalized content for an engaging user experience. - App Integration: Seamlessly integrating third-party apps to extend functionality. - E-commerce Optimization: Enhancing store performance and conversion rates. - Responsive Design: Ensuring a flawless shopping experience across all devices. - API Proficiency: Leveraging APIs for seamless data exchange and functionality. - Problem-Solving: Analyzing challenges and providing innovative solutions.

✅ 3700+ Development Hours ✅ 50+ Successful Projects ✅ 7+ Years of Professional Experience ✅ Specialist in Scalable SaaS, APIs & Integrations ✅ Proven Track Record in Building Business-Ready Applications I’m a Full Stack Web Developer with 7+ years of experience designing, developing, and scaling modern web applications, from SaaS platforms and CRMs to marketplaces and automation tools. I help startups and growing businesses turn ideas into production-ready products through clean code, clear communication, and a focus on business outcomes. 💻 Expertise Backend Development: Scalable RESTful APIs and microservices using Ruby on Rails and Node.js. Frontend Development: Responsive and dynamic UIs with ReactJS, VueJS, AngularJS, JavaScript (ES6), HTML5, CSS3, Tailwind, and Bootstrap. Database Management: Expert in PostgreSQL, MySQL, Redis, MongoDB, and Firebase for secure, high-performance data storage. DevOps & Cloud: Hands-on with AWS, Docker, and Heroku, ensuring smooth deployments, CI/CD pipelines, and scalable architectures. Integrations & Automation: Seamless integrations with Stripe, PayPal, Paystack, and third-party APIs (CRM, chat, analytics, etc.). Quality & Collaboration: Practicing TDD, Agile workflows, and version control via GitHub, GitLab, and Jira for reliable, high-quality delivery. Let’s collaborate to build something exceptional, whether it’s a SaaS platform, custom dashboard, or API-powered business application. I’m open to both short-term and long-term engagements. Keywords: Full-Stack Development | Web App Development | API Development | Ruby on Rails | React.js | Vue.js | Node.js | Angular.js | AWS | Heroku | Docker | PostgreSQL | MySQL | MongoDB | Firebase | RESTful APIs | SaaS | Business Automation | Marketplace Development | Stripe | PayPal | Integrations | Frontend | Backend | TDD | Scalable Apps | Cloud Deployment | Agile | Performance Optimization

I'm a Ruby developer and has been working with Ruby/Rails over 10 years. I have experience with Rails 4 - 7, Heroku/Docker/AWS, React/Vue/Hotwire, Bootstrap/TailwindCSS. I have experience building SAAS & complex custom apps.

Looking for a Ruby on Rails engineer who has been through the full lifecycle of real-world software — building, scaling, debugging, securing, modernizing, and rescuing production systems? I’m Derek Owusu-Frimpong, a Senior Ruby on Rails Engineer with professional Ruby experience since 2016 and a Top Rated Upwork profile with a 100% Job Success Score. I help startups, founders, and engineering teams build, scale, secure, modernize, and rescue production Rails applications across SaaS, fintech, education, healthcare, e-commerce, marketplaces, CRM, HR, and recruitment platforms. My work spans greenfield development, legacy modernization, performance optimization, database/query tuning, background jobs, API development, secure authentication and authorization, OAuth2, payment integrations, Hotwire, Turbo, Stimulus, ActionCable, testing, refactoring, and production debugging. Clients hire me when they need an engineer who can understand a codebase quickly, make sound technical decisions, communicate clearly, take ownership, and deliver reliable, maintainable software that performs well in the real world. If you need an experienced Rails engineer who can move fast without sacrificing quality, I’d be glad to help.

🥇 𝗧𝗼𝗽 𝗥𝗮𝘁𝗲𝗱 𝗣𝗟𝗨𝗦 | ⏳ 𝟰+ 𝗬𝗲𝗮𝗿𝘀 𝗼𝗳 𝗘𝘅𝗽𝗲𝗿𝗶𝗲𝗻𝗰𝗲 | ⭐ 𝟰.𝟵 𝘀𝘁𝗮𝗿𝘀 𝗿𝗮𝘁𝗲𝗱 | 𝟭𝟬𝟬% 𝗖𝗹𝗶𝗲𝗻𝘁 𝗥𝗲𝗰𝗼𝗺𝗺𝗲𝗻𝗱𝗲𝗱. ✮✮✮✮✮ Go from zero to MVP. Then MVP to full scale. ✮✮✮✮✮ ✅ 6000+ Hours logged on UpWork. ✅ 5 Star Reviews. ✅ 4+ Years of experience in Web app development 𝗣𝗿𝗶𝗺𝗮𝗿𝘆 𝗘𝘅𝗽𝗲𝗿𝘁𝗶𝗲𝘀: ✔ Ruby on Rails development ✔ Frontend: React Js, jQuery/Javascript, CoffeeScript ✔ Front-End Development | HTML5/CSS3, TailwindCSS, Bootstrap5 - JavaScript Frameworks | jQuery, React ✔ HAML, CSS3 ✔ Git ✔ Databases: Postgres, MongoDB, MYSQL ✔ API development: RESTful APIs ✔ Testing: RSpec & Capybara and have done TDD /BDD ✔ DevOps: Comfortable handling server setups & deployments and have experience working with dedicated servers, Amazon EC2, Heroku. ✔ Methodology: Agile & Scrum/Kanban methodologies and great communication skills. ✔ Task Management: Trello,Asana,Jira,Basecamp 🔰 I am a passionate and Top Rated web developer who loves to develop new ideas. To utilize my capabilities and technical skills to bring out the best of me and to be active and flexible in the ever-changing technological environment. If you choose to work with me, I can guarantee you that I will provide: ➜ Quick on-time delivery. ➜ Good communication and Regular updates on the project status. ➜ Clean and optimized code. ➜ Unlimited revisions till you are satisfied. 💻 𝗧𝗲𝗰𝗵𝗻𝗶𝗰𝗮𝗹 𝗦𝗸𝗶𝗹𝗹𝘀: 👉 I have more than 3 years of Hands on experience in Ruby on Rails, jQuery, HTML5, CSS3, HAML, SASS, MySQL, PostgreSQL, and Redis. 👉 I have worked on many enterprise applications and successfully handled their front end using HTML, Angular, CSS, jQuery, Bootstrap and back end using Rails, MySql, Postgres based on TDD/BDD development techniques.

My specific expertise is web design and development in the Ruby-on-Rails and WordPress frameworks. I have experience in AI-based vibe coding, AI integration and AI product troubleshooting/completion. I provide the entire website life-cycle: web design, development and web site maintenance. I develop sites for all levels - startup to full enterprise site. One of the highest-rated developers on UpWork - with a "Top-Rated" badge and a 100% job success rating. I focus on efficiency and quality. I do not provide you with a 'less than credible' price estimate then leave you with a broken or unfinished product. I stand ready to help large and small entrepreneurs successfully build their website or web app while respecting their unique budget constraints.

Hey there! 👋 Ruby on Rails development is EXACTLY my expertise! I'm a passionate developer who loves turning ideas into reality through code. After diving deep into Rails development for the past few years, I've gotten pretty good at building everything from sleek web apps to powerful APIs. For now, my primary focus is back-end development using Rails, PostgreSQL, and MongoDB. In addition, I have front-end experience and am currently learning React.js, which allows me to speak the same language as your front-end developers, collaborate smoothly with them, and even assist with front-end tasks when needed. I take pride in writing clean, well-tested code (RSpec is my go-to), and I genuinely enjoy solving complex problems - from optimizing database queries to structuring efficient APIs. I've worked with international teams before and feel confident in my communication skills and ability to fit into your workflow. I care not just about code, but also about your business needs. I can help build something you'll actually be proud of. Write me back - I'm ready to jump in.

Experienced software professional specializing in frontend development, database management, web frameworks, cloud deployment, automated testing, and emerging technologies. Proficient with Ubuntu 24.04 and dedicated to ongoing innovation in the tech industry. Demonstrated commitment to staying ahead of technological advancements through work with Open AI and Claude API.