sugiarto u.

Senior Backend Engineer | Shopify, API & System Integration

I am a Senior Backend Engineer with 15+ years of experience building, maintaining, modernizing, and deploying web applications. My core experience is Ruby on Rails, with strong expertise in Shopify, API and system integration, background processing, search, payments, and production infrastructure. I work directly with clients and can handle projects from backend development and integrations through deployment and production troubleshooting. ### Shopify & API Integration I build custom Shopify solutions and integrations using Shopify REST APIs, GraphQL, webhooks, and background processing. My experience includes Shopify Plus middleware connecting stores with external business systems such as Microsoft Dynamics 365, SFTP, and SureTax, including order processing, data transformation, regional business rules, retries, polling, and automated notifications. I also integrate third-party systems using REST APIs, OAuth 2.0, GraphQL, and webhooks, including payment, tax, ERP, communication, and other external services. ### Backend Engineering My backend experience includes Ruby on Rails, Sidekiq, Redis, PostgreSQL, MySQL, and Elasticsearch. I use Sidekiq for asynchronous processing and can design separate queues and concurrency levels for different workloads. When configuring worker concurrency, I consider Rails database connection pool limits so background jobs do not consume all available database connections and negatively affect web requests or other workers. I also have experience using Elasticsearch for fast search and filtering in Rails applications where relational database queries alone are not sufficient. ### Infrastructure & Deployment I can set up production environments from scratch on Linux VPS servers, including SSH access, Ubuntu/Linux configuration, Nginx, SSL, databases, Redis, background workers, and application deployment. I use Docker and Docker Compose for containerized environments and have experience with Kamal, GitHub Actions, and CI/CD pipelines. My infrastructure experience includes DigitalOcean, AWS, and Heroku. This allows me to troubleshoot issues across both the application and server layers rather than treating deployment and infrastructure as a separate concern. ### Payments I have extensive experience with Stripe integrations, including subscriptions, webhooks, Payment Intents, and custom payment and invoice workflows. I also have experience with PayPal integrations. ### Frontend & Full-Stack Development Although my primary focus is backend engineering, I also have substantial frontend experience and can work across the stack when needed. I have used Vue.js, Hotwire/Turbo, Stimulus.js, and Tailwind CSS to build and modernize interactive web interfaces. ### Legacy Rails Modernization I work with both legacy and modern Rails applications, including upgrading older Rails versions, resolving dependency and compatibility issues, improving application architecture, and moving applications toward modern development and deployment workflows. ### AI-Assisted Development I use modern AI-assisted coding tools such as OpenCode to accelerate code exploration, implementation, debugging, refactoring, and working with unfamiliar codebases. I treat AI as an engineering tool rather than relying on generated code blindly. I review, test, validate, and integrate changes as part of my normal development workflow. If you need a senior engineer who can work across backend development, Shopify integrations, APIs, infrastructure, and production troubleshooting, feel free to share your current stack and the problem you are trying to solve.