Building a Lightweight, High-Performance Blog with Deno and Clean Architecture
How to build a fast personal website with Deno, Hono, Ports and Adapters architecture, and vanilla CSS.
Lead Frontend Engineer @ On • Berlin, DE
Frontend systems architecture and engineering leadership.
I am Cezar Sampaio, a Lead Engineer based in Berlin with 15 years of experience. I design scalable web architectures, guide multidisciplinary teams, and connect product strategy with reliable technical execution.
On (Lead)
C&A Europe
Overdeck
Trade Republic
Contentful
HelloFresh
EBANX
15+
Years Leading Squads & Building Scalable Systems
20M+
Users Served Across Global Web Platforms
8+
High-Growth Tech Companies & Startups
10+
Open Source Tools & Web Packages
Track Record
Recent Experience
Key leadership and senior engineering roles shaping scalable platforms.
Lead Frontend Engineer • On
Nov 2024 – PresentLead frontend architecture initiatives for On’s global e-commerce platform. Implemented server-side rendering with edge caching to improve Core Web Vitals, refactored navigation, and guided cross-functional delivery for commercial features.
Senior Frontend Engineer & EM • C&A Europe
May 2023 – Nov 2024Led engineering projects across the digital department. Migrated 15 million users to Auth0 under GDPR compliance and managed the decoupling of authentication and wishlist systems into microservices.
Senior Frontend Engineer • Trade Republic
May 2022 – Feb 2023Built reliable payment workflows and web interfaces in Vue.js and TypeScript for the Payments squad.
Senior Software Engineer • Contentful
Mar 2020 – Apr 2022Developed core platform features across the headless CMS product using React, TypeScript, and Node.js microservices.
Writing & Thoughts
Blog
My personal space to write about anything.
Open Source & Side Projects
Selected creations
tinytivity
Open SourceA zero-dependency, fully typed reactive state library for JavaScript and TypeScript. Published on JSR and compatible with all JavaScript runtimes.
Overdeck
Co-FounderA companion & controller ecosystem for content creators and streamers. Built with Next.js, Node.js, and Electron for desktop, and React Native for mobile applications.
react-fake-content
NPM LibraryA lightweight, zero-dependency placeholder component library for React to render skeleton states during asynchronous data fetching.
react-bucket-test
NPM LibraryA React library to easily configure and run client-side A/B bucket tests with multi-provider tracking (e.g. Google Tag Manager).