David L.
Senior Full Stack Engineer
Experience
Apr 2024 - Aug 2025
1 year 5 monthsGreece
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 monthsAustria
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 monthsAustria
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 monthsAustria
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 monthsHong 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 realtime 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.
Languages
Chinese
NativeEnglish
AdvancedGerman
IntermediateEducation
Oct 2018 - Jun 2022
Graz University of Technology
Bachelor’s Degree · Computer Science · Graz, Austria · 3.9
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