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Hi, I'm Krzysztof Sedlak, a Senior Full Stack Engineer with over 11 years of experience in designing and delivering scalable, high-performance systems. I've worked across various industries including e-commerce, fintech, and platform infrastructure, focusing on modernizing architectures with containerization, real-time systems, and cloud-native microservices. I enjoy leading teams and mentoring juniors, always emphasizing clean design patterns and system observability. I'm comfortable working remotely with globally distributed agile teams, and I like to streamline workflows using cutting-edge technologies like GraphQL, Kubernetes, and Terraform to deliver value quickly and reliably.…Hi, I'm Krzysztof Sedlak, a Senior Full Stack Engineer with over 11 years of experience in designing and delivering scalable, high-performance systems. I've worked across various industries including e-commerce, fintech, and platform infrastructure, focusing on modernizing architectures with containerization, real-time systems, and cloud-native microservices. I enjoy leading teams and mentoring juniors, always emphasizing clean design patterns and system observability. I'm comfortable working remotely with globally distributed agile teams, and I like to streamline workflows using cutting-edge technologies like GraphQL, Kubernetes, and Terraform to deliver value quickly and reliably.

Krzysztof Sedlak

Full Stack Developer, Developer, Back-End Developer, +2

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Hi, I'm Krzysztof Sedlak, a Senior Full Stack Engineer with over 11 years of experience in designing and delivering scalable, high-performance systems. I've worked across various industries including e-commerce, fintech, and platform infrastructure, focusing on modernizing architectures with containerization, real-time systems, and cloud-native microservices. I enjoy leading teams and mentoring juniors, always emphasizing clean design patterns and system observability. I'm comfortable working remotely with globally distributed agile teams, and I like to streamline workflows using cutting-edge technologies like GraphQL, Kubernetes, and Terraform to deliver value quickly and reliably.…Hi, I'm Krzysztof Sedlak, a Senior Full Stack Engineer with over 11 years of experience in designing and delivering scalable, high-performance systems. I've worked across various industries including e-commerce, fintech, and platform infrastructure, focusing on modernizing architectures with containerization, real-time systems, and cloud-native microservices. I enjoy leading teams and mentoring juniors, always emphasizing clean design patterns and system observability. I'm comfortable working remotely with globally distributed agile teams, and I like to streamline workflows using cutting-edge technologies like GraphQL, Kubernetes, and Terraform to deliver value quickly and reliably.

Available to hire

Hi, I’m Krzysztof Sedlak, a Senior Full Stack Engineer with over 11 years of experience in designing and delivering scalable, high-performance systems. I’ve worked across various industries including e-commerce, fintech, and platform infrastructure, focusing on modernizing architectures with containerization, real-time systems, and cloud-native microservices.

I enjoy leading teams and mentoring juniors, always emphasizing clean design patterns and system observability. I’m comfortable working remotely with globally distributed agile teams, and I like to streamline workflows using cutting-edge technologies like GraphQL, Kubernetes, and Terraform to deliver value quickly and reliably.

Skills

Experience Level

Expert

Expert

Expert

Expert

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Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Language

English

Advanced

Polish

Fluent

Work Experience

Senior Software Engineer at BEIT

June 30, 2025 - July 14, 2025

Re-architected legacy monoliths into containerized microservices, reducing system downtime by 30% and aligning services with business goals. Led backend design in Node.js and Go, using GCP Cloud Tasks and Pub/Sub for asynchronous workflows. Spearheaded GraphQL API adoption improving request latency by ~40ms and simplifying frontend integration. Developed reusable React components with TypeScript and Tailwind to enable faster and consistent UI delivery across teams. Introduced secure RBAC and audit logging integrated with AWS CloudWatch for compliance. Authored reusable Terraform modules, cutting infrastructure onboarding time by 50%. Modernized CI/CD pipelines with GitHub Actions and ArgoCD, reducing deployment rollback issues. Migrated services to Docker/Kubernetes improving health checks and rollout reliability. Reviewed code and mentored junior engineers in design patterns, error handling, and observability. Worked in 2-week sprints delivering features ahead of schedule.

Senior Software Engineer at ViSenze

December 31, 2023 - July 14, 2025

Led design of multi-tenant GraphQL APIs supporting 20+ B2B e-commerce platform integrations. Built frontend SDKs and Next.js modules for Shopify, Magento, and WooCommerce including OAuth and Stripe payment flows. Engineered payment microservices in Go supporting 5K+ concurrent orders with 15% latency reduction. Deployed services using AWS CloudRun, S3, and ECS achieving 99.9% uptime. Optimized PostgreSQL queries with caching and batching reducing load times by 25%. Improved API discoverability with OpenAPI docs, easing partner integrations by 40%. Developed CI/CD processes using GitHub Actions, Jenkins, and blue/green deployments. Revamped React UI for image-based search reducing GraphQL query latency by 60ms. Integrated Redis caching to accelerate ranking models. Extended backend GraphQL resolvers in Django. Partnered with ML teams to visualize CV model confidence scores. Delivered A/B testing frameworks increasing CTR by 9.4%.

Full Stack Developer at Shopee

December 31, 2019 - July 14, 2025

Developed vendor portals and catalog tools using React, Angular, and Vue, driving early platform adoption. Created backend APIs in Node.js and Django with robust authentication and caching. Maintained admin dashboards for 1K+ support agents focusing on usability and performance. Optimized MySQL queries reducing DB load by 18%. Built merchant onboarding flow reducing signup time by 35%. Enabled real-time logistics tracking with WebSockets. Championed Docker local dev environments and contributed to its early adoption across teams. Co-led hackathon projects including a bulk product uploader tool adopted in production.