Matas K.
Senior Full Stack Engineer
Experience
Sep 2024 - Present
1 year 3 monthsZürich, Switzerland
Senior Full Stack Engineer
Farmy
- Architected and implemented Java Spring Boot microservices for order management and inventory synchronization, reducing stock-out incidents by 20% through event-driven Kafka pipelines.
- Built React frontends with Hooks and Redux Toolkit, improving UI responsiveness for 50k+ monthly active users.
- Introduced AI-driven dynamic pricing engine (Python ML services integrated with Java APIs), increasing gross margin by 8%.
- Migrated critical modules to AWS EKS + Terraform, ensuring scalability during peak demand and achieving 99.95% uptime.
- Implemented CI/CD pipelines with GitHub Actions and Docker, cutting release cycles from 2 weeks to 3 days.
- Designed GraphQL APIs for mobile app integrations, supporting customer and vendor-facing applications.
- Applied hexagonal architecture principles to decouple domain logic from infrastructure, improving testability and maintainability.
- Enhanced caching strategies with Redis and database optimization in PostgreSQL, reducing checkout API latency by 30%.
- Developed blockchain prototype for farm-to-table traceability, enabling transparent product origin tracking.
- Mentored junior engineers on Java microservices, React optimization, and cloud-native best practices, improving team delivery velocity by 15%.
Nov 2020 - Sep 2023
2 years 11 monthsPrague, Czech Republic
Full Stack Engineer
Mews
- Developed Java Spring Boot reservation and billing services, processing 1M+ monthly transactions across hotels and hostels.
- Built React dashboards for hospitality managers with real-time booking visualization, improving operational decision-making speed.
- Integrated AI-powered demand forecasting models into the booking pipeline, reducing overbooking incidents by 12%.
- Migrated monolith modules to Kubernetes-based microservices with CI/CD automation, increasing release frequency by 40%.
- Designed and exposed REST/GraphQL APIs to third-party booking providers, enabling faster onboarding of B2B integrations.
- Improved payment flow by implementing blockchain-based smart contracts for secure deposits, reducing disputes.
- Applied CQRS and event sourcing patterns for financial transactions, improving auditability and system reliability.
- Automated testing (JUnit, Jest, Cypress) and monitoring (Datadog, ELK Stack), reducing production issues by 25%.
- Refactored legacy AngularJS modules to React with TypeScript, cutting frontend technical debt.
- Mentored cross-functional teams on clean architecture and API-first design, improving collaboration across frontend, backend, and DevOps.
Feb 2018 - Oct 2020
2 years 9 monthsKaunas, Lithuania
Full Stack Developer
Sanitas
- Built Java Spring Boot APIs for patient records and prescription tracking, ensuring compliance with healthcare data regulations.
- Designed Angular dashboards for doctors and pharmacists, enabling real-time access to medical histories.
- Integrated AI-based symptom checker module (Python NLP with Java APIs), reducing unnecessary clinic visits by 10%.
- Deployed services to Azure Kubernetes Service (AKS), improving scalability for regional hospital networks.
- Developed blockchain-based prototype for prescription authenticity validation, reducing fraud risk.
- Implemented CI/CD pipelines with Jenkins and Docker, reducing deployment errors by 35%.
- Optimized Hibernate queries and applied Redis caching, improving patient data retrieval by 25%.
- Collaborated with mobile team to design backend APIs for Android/iOS apps, ensuring consistent data access.
- Conducted unit and integration testing with JUnit, Mockito, and Selenium, raising automated coverage to 85%.
- Applied DDD (Domain-Driven Design) for healthcare modules, simplifying future enhancements and integrations.
Jul 2016 - Feb 2018
1 year 8 monthsKaunas, Lithuania
Web Developer
TeleSoftas
- Developed Java-based backend modules and AngularJS/React frontends for client-facing projects across finance and logistics.
- Implemented microservices for invoice management using Spring Boot and REST APIs, streamlining processing for enterprise clients.
- Built React dashboards with Redux for delivery tracking systems, improving user satisfaction scores by 15%.
- Assisted in deploying applications to AWS (EC2, RDS, S3) with Docker-based workflows, ensuring 99% uptime.
- Introduced AI-driven OCR module for document scanning and invoice recognition, reducing manual data entry by 30%.
- Implemented CI/CD pipelines with Jenkins, enabling continuous deployments and faster delivery to clients.
- Improved performance by optimizing SQL queries and implementing Redis caching layers.
- Collaborated with mobile developers to design backend APIs for cross-platform applications.
- Wrote automated tests with JUnit, Selenium, and Jest, improving release reliability.
- Participated in architectural reviews, contributing to decisions on migrating legacy systems to modern Java + React stacks.
Summary
Senior Full Stack Developer with 8+ years of experience designing and delivering high-performance applications using Java (Spring Boot, Hibernate) and React/Angular. Proven track record in building cloud-native, microservices-based architectures across SaaS, healthcare, hospitality, and e-commerce domains. Skilled in integrating AI/ML-driven modules, optimizing system scalability through DevOps automation (CI/CD, Kubernetes, Terraform), and applying architectural concepts such as hexagonal architecture for maintainability. Adept at mentoring teams, implementing blockchain-based modules for secure transactions, and consistently delivering measurable improvements in system performance, user engagement, and business outcomes.
Languages
English
AdvancedLithuanian
AdvancedCzech
ElementaryGerman
ElementaryEducation
Oct 2012 - Jun 2016
Kaunas University of Technology
Bachelor of Science · Informatics · Kaunas, Lithuania
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