Recommended expert

David Lynn

Senior Full Stack Engineer

David Lynn
Hallein, Austria

Experience

Apr 2024 - Aug 2025
1 year 5 months
Greece

Senior Full Stack Engineer

Fractual

  • Built and maintained a full-featured React Native mobile app and companion web portal supporting multi-role access and real-time collaboration for service teams.
  • Developed a robust NestJS backend using TypeScript, adhering to scalable microservices patterns to support a dynamic task management system.
  • Designed and optimized PostgreSQL schemas, using advanced indexing and normalized data models to support patient tracking, tasks, and outcome reporting.
  • Integrated Socket.IO to support real-time team communication, task status updates, and instant notifications across mobile and web platforms.
  • Developed secure authentication workflows using AWS Cognito, including multi-role login, token refresh, and session timeout handling.
  • Leveraged AWS S3 for secure document uploads (patient records, resource materials) with signed URLs and access control policies.
  • Connected AWS SNS and SES to automate notifications for escalations, missed follow-ups, and appointment reminders.
  • Engineered an admin analytics dashboard using React + Zustand for tracking user activity, case completion rates, and compliance metrics.
  • Designed and implemented AI-driven features for task prioritization and patient risk classification using external API integrations.
  • Established a robust CI/CD pipeline using GitHub Actions and Docker, achieving automated testing, linting, and environment-based deployments.
  • Followed Agile ceremonies (daily standups, sprint planning, retros) while collaborating with QA, BAs, and PMs to deliver high-velocity features.
  • Led data protection efforts ensuring full GDPR compliance, including encrypted storage, session control, and user-consent management.
  • Delivered a fully responsive UI using DaisyUI-style components for mobile and tablet-first designs, achieving high Lighthouse scores.
  • Reduced support tickets by 40% by implementing detailed audit logging and a self-service helpdesk system in the admin interface.
Apr 2022 - Feb 2024
1 year 11 months
Austria

Full Stack Engineer

Porsche Informatik GmbH

  • Designed and deployed a mobile-first React Native app for AI-powered interactive storytelling, integrated with a backend using NestJS and AWS Lambda.
  • Created scalable, event-driven backend workflows using AWS Step Functions, managing asynchronous media generation tasks.
  • Built and secured REST APIs and WebSockets in NestJS, including validation (Zod-style), pagination, and rate limiting for safe consumption.
  • Designed and implemented relational models in PostgreSQL, optimized for large-scale content personalization and multilingual storage.
  • Leveraged Cognito for user authentication and role control, with custom user pools, triggers, and token lifecycle configuration.
  • Integrated AWS S3 for secure storage of images, audio, and user uploads; implemented lifecycle rules for cleanup and cost control.
  • Connected SES/SNS for user email verification, usage alerts, and marketing triggers.
  • Set up robust CI/CD automation with GitHub Actions, Docker, and Azure DevOps, supporting multiple testing stages and release channels.
  • Built AI prompt pipelines with GPT-4 for generating safe, age-appropriate content, and fallback handling for failures.
  • Created admin and parental dashboards using React and Zustand, supporting content approvals, session logs, and preference settings.
  • Reduced crash rates by 25% by instrumenting Sentry, AWS CloudWatch, and Firebase Performance Monitoring across the stack.
  • Delivered offline-first architecture, using caching and sync logic for low-connectivity scenarios.
  • Mentored 3 junior developers and introduced cross-squad documentation to scale velocity.
  • Maintained high test coverage with Jest, MSW, and React Testing Library, ensuring regression-free deployments.
Feb 2020 - Dec 2022
2 years 11 months
Austria

Senior Full Stack Developer

Toptal

  • Migrated a legacy monolith into modular NestJS microservices supporting inventory, order, and logistics domains.
  • Created highly available REST and Socket.IO-based APIs with auto-scaling support using Docker and Kubernetes.
  • Developed a PostgreSQL-backed event pipeline for warehouse operations, stock audits, and fulfillment tracking.
  • Built a web-based inventory control dashboard in React + Zustand, supporting role-based access and real-time data.
  • Engineered task scheduling tools with granular filters (SKU, supplier, urgency), similar to healthcare dispatch systems.
  • Integrated AWS SNS/SQS for decoupled service communication and order lifecycle automation.
  • Designed barcode and RFID scanning features in a React Native app, used in-store and in fulfillment centers.
  • Maintained user authentication with Cognito and OAuth2, using refresh tokens and RBAC enforcement.
  • Enabled offline-first stock reconciliation with delta sync and caching for mobile field devices.
  • Built audit trails and access logs for compliance and reporting needs.
  • Led sprint planning, backlog refinement, and code reviews for a 10-person full-stack team.
  • Reduced query latency by optimizing PostgreSQL indexes, materialized views, and cache layers (Redis).
  • Set up and maintained CI/CD with Azure DevOps, enabling automatic build, test, and blue/green deployments.
  • Aligned architecture with operational KPIs from cross-functional logistics and ops teams.
Jul 2019 - Feb 2020
8 months
Austria

Full Stack Engineer

Redox Interactive

  • Created a custom high-performance shopping platform with a mobile-first React.js/Next.js UI, leveraging Server-Side Rendering (SSR) to enhance SEO and cut page load times by 30%.
  • Engineered real-time inventory and checkout workflows using Node.js, Express.js, and TypeScript, integrated with AWS Lambda, DynamoDB, and PostgreSQL for accurate stock visibility, safe concurrency handling, and high-traffic resilience.
  • Deployed a robust payment and invoicing system supporting card payments, refunds, and tax-inclusive invoicing, incorporating Stripe APIs, secure payment flows, and email-based invoice delivery.
  • Architected a modular order management engine with support for cart persistence, discount logic, purchase history, and guest checkout — all exposed through RESTful APIs.
  • Implemented analytics and behavior tracking using Google Analytics, Mixpanel, and custom event pipelines, enabling actionable insights across user journeys, product performance, and conversion rates.
  • Optimized frontend performance with lazy loading, dynamic imports, and asset tuning via Next.js, React Query, and Tailwind CSS, ensuring seamless experiences across mobile and desktop.
  • Transitioned complex global state management from Redux to React Query and Zustand, improving maintainability, bundle size, and developer velocity.
  • Delivered secure authentication and session workflows with JWT, OAuth2, and MFA, ensuring privacy, account safety, and compliance with e-commerce security standards.
  • Expanded test coverage across the stack using Jest, React Testing Library, MSW, and Postman, reducing regression issues by 40% and improving deployment confidence.
  • Facilitated Agile ceremonies, led code reviews, and partnered with design and backend squads, shipping features through CI/CD pipelines in Azure DevOps.
May 2017 - Jan 2019
1 year 9 months
Hong Kong

Junior Full Stack Developer

SO technology

  • Supported internal tooling and mobile dashboards for SO technology, enabling scaled operations across logistics, product, and finance teams.
  • Developed and maintained high-visibility internal SPAs and dashboards using React.js, Vanilla JS, and jQuery, providing interactive data visualizations, real-time search filters, and drag-and-drop reporting features.
  • Built RESTful APIs and data models using Laravel (PHP 7, Symfony components) with PostgreSQL, enabling seamless integration between frontend dashboards and backend services.
  • Designed and deployed mobile-first dashboards with React Native (Expo), giving warehouse managers and field agents real-time access to logistics tools.
  • Integrated device capabilities such as barcode scanning, push notifications, and geolocation using Expo SDK modules to streamline delivery and tracking workflows.

Summary

Seasoned Senior Full Stack Engineer with 10+ years of experience building scalable web and mobile applications across real estate, fintech, gaming, and data-driven industries. Expert in JavaScript and TypeScript, with a strong focus on React, Next.js, Tailwind CSS, Node.js, Golang, .NET, and microservices. Proficient in developing SPAs, SSR apps, and microfrontends, and integrating RESTful APIs, GraphQL, event-driven systems, and cloud-native solutions using AWS, Docker, and CI/CD. Known for writing clean, performant code, leading Agile teams, mentoring engineers, and driving architecture that enhances scalability and delivery speed.

Skills

Frontend

  • Javascript
  • Typescript
  • React
  • React Native
  • React Hooks
  • Redux
  • Bootstrap
  • Jquery
  • Angular
  • Vue.js
  • Next.js
  • Tailwind Css
  • Mui
  • Flutter
  • Svelte.js
  • Nuxt.js
  • Vuex
  • Shadcn Ui
  • Responsive Design
  • Zustand
  • Pinia
  • Css3
  • Ngrx
  • Rx.js
  • Html5

Backend

  • Node.js
  • Typescript
  • Express
  • Nest.js
  • Rest
  • Graphql
  • Jwt
  • Oauth2
  • Rabbitmq
  • Kafka
  • Redis
  • Docker
  • Aws Lambda
  • Azure Devops
  • Postgresql
  • Mongodb
  • Mysql
  • Kubernetes
  • Grpc
  • Entity Framework Core
  • Prisma
  • C#
  • Asp.net Core
  • Github Actions
  • Terraform
  • Sentry

Others

  • Git
  • Github
  • Scrum
  • Agile
  • Google Analytics
  • Agile Methodologies
  • Problem-solving Abilities
  • Code Reviews
  • Database Management
  • Mentoring Junior Developers

Languages

Chinese
Native
English
Advanced
German
Intermediate

Education

Oct 2018 - Jun 2022

Graz University of Technology

Bachelor’s Degree in Computer Science · Computer Science · Graz, Austria · 3.9

Need a freelancer? Find your match in seconds.
Try FRATCH GPT
More actions

Similar Freelancers

Discover other experts with similar qualifications and experience

Jürgen Fey
Jürgen Fey

AR/VR/XR Architect

View Profile
Florian Faist
Florian Faist

Freelance Senior Developer

View Profile
Satya Vulise
Satya Vulise

Lead Developer

View Profile
Ioan Dobre
Ioan Dobre

Senior Software Developer

View Profile
Serge Kalinin
Serge Kalinin

MLOps (machine learning operations)

View Profile
Andreas Kraus
Andreas Kraus

Senior Developer

View Profile
Achille Chimi
Achille Chimi

Backend/Frontend Developer

View Profile
Alexander Kapincev
Alexander Kapincev

Senior Fullstack Developer

View Profile
Timm Preetz
Timm Preetz

Senior Backend-Framework Engineer

View Profile
Robin Ochsner
Robin Ochsner

Co-Founder & AI Solutions Architect

View Profile
Ales Loncar
Ales Loncar

Senior DevOps Consultant (Freelance)

View Profile
Siegfried-thor Bolz
Siegfried-thor Bolz

AI Solutions Architect & Developer

View Profile
Michael Rudl
Michael Rudl

Software Developer

View Profile
Werner Keil
Werner Keil

Test Coordinator, Designer and Engineer

View Profile
Dirk Bolte
Dirk Bolte

Senior Software Developer

View Profile
Fady Kuzman
Fady Kuzman

Senior Software Developer / Tech Lead

View Profile
Jamal Baydoun
Jamal Baydoun

Freelance Software Architect & Developer

View Profile
Stanislav Bilik
Stanislav Bilik

Senior Solution Architect

View Profile
Benedikt Buchner
Benedikt Buchner

Fullstack Developer

View Profile
Thomas Hoefkens
Thomas Hoefkens

Senior MLOps, DevOps Engineer

View Profile
John Ampia-addison
John Ampia-addison

Senior DevOps Engineer

View Profile
Emre Ates
Emre Ates

Development of a software solution for archiving and a GenAI-based Q&A tool

View Profile
Kurt Blumenschein
Kurt Blumenschein

Backend- / Micro-Service Developer, DevOps, Test automation

View Profile
Marijn Scholtens
Marijn Scholtens

Senior Software Engineer

View Profile
Matthias Freelancer
Matthias Freelancer

Business Architect

View Profile
Alexey Gravanov
Alexey Gravanov

Cloud Architect & DevOps, Head of Architecture

View Profile
Cristian Serje reyes
Cristian Serje reyes

Team Lead Mobile Native Apps

View Profile
Nikolaus Jäger-grassl
Nikolaus Jäger-grassl

Integration Architect

View Profile
Marcel Meyer
Marcel Meyer

Cloud-Architect, Senior Solution Architect, Senior Software-Engineer

View Profile
Hicham Mokhtari
Hicham Mokhtari

Freelance Software Developer

View Profile