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I am a Senior Full-Stack Engineer with 10+ years of experience designing, building, scaling, and operating SaaS platforms, fintech products, AI-powered applications, and cloud-native systems. For the past 5 years, I have been working at Money Forward, one of Japan's leading fintech companies, where I contribute as a Full-Stack Engineer and a key player in platform engineering initiatives. My responsibilities span application development, cloud infrastructure, CI/CD automation, Kubernetes operations, performance optimization, disaster recovery, observability, and scalable system architecture. Over the last 2 years, I have also focused heavily on AI-powered solutions, helping clients build applications using OpenAI models, GPTScript, AI agents, workflow automation, and LLM integrations. My strength is not only building software but also ensuring that systems remain scalable, reliable, observable, and cost-efficient in production environments. Technical Expertise Backend Development • Ruby on Rails • Node.js / Express • Python (Flask, Django) • Go • Elixir / Phoenix Frontend Development • React • JavaScript / TypeScript • HTML/CSS • jQuery Cloud & Platform Engineering • AWS • Kubernetes (EKS) • Docker • Terraform • CI/CD Pipelines • Infrastructure as Code • Auto Scaling • Disaster Recovery • Performance Optimization Observability & Reliability • Datadog (APM, Logs, Dashboards, Monitors, SLOs) • Grafana • Rollbar • Distributed Tracing • Incident Investigation & Root Cause Analysis • Production Monitoring • Capacity Planning • Cost Optimization AI Development • OpenAI API • GPTScript • AI Agents • Prompt Engineering • Workflow Automation • LLM Integrations • RAG-based Applications What I Can Help With • Build SaaS products from idea to production • Modernize and upgrade legacy applications • Design scalable cloud-native architectures • Implement Kubernetes and DevOps best practices • Optimize application performance and infrastructure costs • Integrate AI capabilities into existing products • Establish observability and monitoring strategies • Troubleshoot complex production issues • Automate development and deployment workflows Selected Experience • 10+ years of professional software engineering experience • 8+ years of Ruby on Rails development • 5+ years building and operating fintech products at Money Forward Japan • AWS Certified Developer • Successfully delivered AI, automation, SaaS, and cloud infrastructure projects for international clients • Extensive experience working with large-scale production systems and cross-functional engineering teams One of my key strengths is bridging the gap between software development, cloud infrastructure, and production operations. I enjoy solving challenging technical problems and helping businesses build reliable, scalable, and maintainable systems that can grow with their needs. If you are looking for an engineer who can contribute across application development, cloud architecture, DevOps, observability, and AI integration, I would be happy to discuss your project.

Name: Hien Nguyen Sex: Male Nationality: Vietnamese Years of Experience: - 7+ years of experience in programming with Ruby on Rails, Rspec, sidekiq, redis, AWS - 10 years of experience in programming with C#, ASP .NET languages. - Familiar with AWS, Google, Azure clouds, stripe, paypal payment platform.

TOP-RATED Ruby on Rails Developer | 7+ Years in Full-Stack RoR Development MAIN SKILLS: ✓ Expert web development with Ruby on Rails ✓ Experience in client-side scripting such as HTML, JavaScript, JQuery, CSS, Twitter-bootstrap ✓ Experience single page application with ReactJS, VueJS ✓ Experience in Relational DBMS such as Postgresql, MySQL ✓ Experience with e-commerce solutions (Shopify) ✓ Experience in OAuth Authentication (Facebook, Google, Twitter, LinkedIn) ✓ Strong knowledge of popular gems such as Devise, Cancancan, Rolify, Paperclip, etc ✓ Familiar with hosting services such as AWS, Heroku, EngineYard ✓ Experience in deployment scripts such as Capistrano, Mina ✓ In-depth git knowledge ✓ Experience in unit tests with Rspec If you're seeking a Ruby on Rails developer who is passionate about pushing boundaries and delivering excellence, let's connect. I am available for interviews, test projects, and demonstrations to showcase my proficiency in Ruby on Rails development. Your satisfaction is my utmost priority, and I am committed to exceeding your expectations.

I am a professional web developer with over 12 years of experience. My current main framework for web development is Ruby on Rails. I started using this framework in 2013 and eventually fell in love with it. Rails has now become a part of my life. Using Ruby on Rails and other technologies, I can realize innovative ideas and turn them into products that add great value to users. I always look for new challenges and never stop improving myself in order to become an expert in the field of web development. My main areas of expertise: + Ruby on Rails + Ruby gems: Devise, Carrierwave, Paperclip, HAML, Capistrano, Resque, Sidekiq, Mongoid and more + TDD and Unit Testing with Cucumber, Rspec, Cabybara + Front-end technologies: AJAX, CSS3, HTML5, jQuery, ReactJS, React-Redux + Mobile-first responsive design: Bootstrap, Zurb Foundation + Relational and NoSQL databases: MySQL, PostgreSQL, MongoDB, Redis + Payment service integration: Paypal, Stripe, Checkout, Inpendium + Deployment platforms: Heroku, AWS, DigitalOcean, VPS + Amazon Web Services: CloudFront, Elastic Load Balancer, OpsWorks, ElasticCache, ElasticBeanstalk, etc + Social network and third-party integration: Google Maps, Google API, Facebook, Twitter + Multilingual web applications + Git workflow + Management tools: Trello, Pivotal Tracker, Redmine, JIRA.

I am a professional web developer with over 10 years of experience. My current main framework for web development is Ruby on Rails. I started using this framework in 2013 and eventually fell in love with it. Rails has now become a part of my life. Using Ruby on Rails and other technologies, I can realize innovative ideas and turn them into products that add great value to users. I always look for new challenges and never stop improving myself in order to become an expert in the field of web development. My main areas of expertise: + Ruby on Rails + Ruby gems: Devise, Carrierwave, Paperclip, HAML, Capistrano, Resque, Sidekiq, Mongoid and more + TDD and Unit Testing with Cucumber, Rspec, Cabybara + Front-end technologies: AJAX, CSS3, HTML5, jQuery, ReactJS, React-Redux + Mobile-first responsive design: Bootstrap, Zurb Foundation + Relational and NoSQL databases: MySQL, PostgreSQL, MongoDB, Redis + Payment service integration: Paypal, Stripe, Checkout, Inpendium + Deployment platforms: Heroku, AWS, DigitalOcean, VPS + Amazon Web Services: CloudFront, Elastic Load Balancer, OpsWorks, ElasticCache, ElasticBeanstalk, etc + Social network and third-party integration: Google Maps, Google API, Facebook, Twitter + Multilingual web applications + Git workflow + Management tools: Trello, Pivotal Tracker, Redmine, JIRA.

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.