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Hi there! I'm Michal Klepaczko, a Senior Software Engineer with 15+ years of experience spanning FinTech, e-commerce, and SaaS. I've built and shipped React Native and Flutter apps with secure APIs, offline storage, biometric login, and push notifications. I focus on performance, scalable backends, and practical, user-centered engineering. I enjoy collaborating with product and design teams to translate complex requirements into reliable, high-quality software and fast feature delivery through robust CI/CD pipelines.…Hi there! I'm Michal Klepaczko, a Senior Software Engineer with 15+ years of experience spanning FinTech, e-commerce, and SaaS. I've built and shipped React Native and Flutter apps with secure APIs, offline storage, biometric login, and push notifications. I focus on performance, scalable backends, and practical, user-centered engineering. I enjoy collaborating with product and design teams to translate complex requirements into reliable, high-quality software and fast feature delivery through robust CI/CD pipelines.

Michal Klepaczko

Full Stack Developer, Web Developer, Back-End Developer, +3

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Hi there! I'm Michal Klepaczko, a Senior Software Engineer with 15+ years of experience spanning FinTech, e-commerce, and SaaS. I've built and shipped React Native and Flutter apps with secure APIs, offline storage, biometric login, and push notifications. I focus on performance, scalable backends, and practical, user-centered engineering. I enjoy collaborating with product and design teams to translate complex requirements into reliable, high-quality software and fast feature delivery through robust CI/CD pipelines.…Hi there! I'm Michal Klepaczko, a Senior Software Engineer with 15+ years of experience spanning FinTech, e-commerce, and SaaS. I've built and shipped React Native and Flutter apps with secure APIs, offline storage, biometric login, and push notifications. I focus on performance, scalable backends, and practical, user-centered engineering. I enjoy collaborating with product and design teams to translate complex requirements into reliable, high-quality software and fast feature delivery through robust CI/CD pipelines.

Available to hire

Hi there! I’m Michal Klepaczko, a Senior Software Engineer with 15+ years of experience spanning FinTech, e-commerce, and SaaS. I’ve built and shipped React Native and Flutter apps with secure APIs, offline storage, biometric login, and push notifications. I focus on performance, scalable backends, and practical, user-centered engineering.

I enjoy collaborating with product and design teams to translate complex requirements into reliable, high-quality software and fast feature delivery through robust CI/CD pipelines.

Skills

Experience Level

Expert

Expert

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Intermediate

Language

English

Fluent

Polish

Fluent

Work Experience

Senior Software Engineer at IN VOI

February 1, 2022 - October 1, 2025

E-commerce & FinTech Platforms using Spring Boot and FastAPI, PostgreSQL, Redis, Elasticsearch; AWS (EC2, Lambda, S3, ECS); Docker; CI/CD with Bitrise, Fastlane, and GitHub Actions; GraphQL & REST APIs; Push Notifications (Firebase); OAuth & Biometric Authentication; SQLite + Offline-First Architecture; Stripe integration; performance optimization (async storage & bundle size). Improved mobile UX, reduced load times, and boosted retention. Implemented offline-first architecture, mobile security measures, and modernized APIs for mobile responsiveness.

Senior Full Stack Developer at SixChain

November 1, 2018 - Present

Led mobile-first, real-time campaign dashboards with Vue.js/Nuxt.js; adaptive layouts from 320px to 1440px; client-side caching with IndexedDB; reverse-engineered ad delivery APIs for progressive loading; event tracking and session heatmaps; integrated mobile ad rendering SDKs; refactored CSS to utility-first SCSS; cross-device testing (BrowserStack); automated preview environments to showcase mobile versions.

Web & Mobile Developer at DevYard

June 1, 2013 - December 31, 2014

Developed responsive SaaS modules with React and Backbone; optimized UI for 3G networks; offline page recovery with local storage; reusable frontend architecture for touch interactions; implemented API retry patterns for unstable networks; lightweight mobile charts to reduce payload; responsive CSS Grid & Flexbox; improved mobile UX and engagement.