Stephan Koglin-Fischer

Fullstack Software Engineer, Solution Architect & AI Context Engineer

Independent software contractor delivering product engineering across industries including automotive, HR tech, e-commerce, and enterprise — working with clients ranging from startups to Siemens.

Senior Manager Frontend Developer

Working on the migration from Angular to React for the sixt-neuwagen.de website, integrating Drupal CMS with GraphQL, and advocating for a monorepo structure.

Frontend Developer

Created a tool for the content team to support the retail platform, implemented UI/UX designs, contributed to PHP Laravel backend development, coached the team, optimized Scrum processes, supported DevOps in deploying applications to Kubernetes.

Product Manager

Quapona Technologies GmbH

Evolved from technical lead into full product ownership — roadmap, stakeholder alignment, and cross-functional delivery.

Senior Software & Cloud Architect

Quapona Technologies GmbH

Joined as C/C++ firmware developer and progressed through iOS, cloud architecture, and software engineering to technical lead over four years at this IoT hardware startup.

Developer

Sedenius Engineering GmbH

Developed a high-performance data acquisition and replay system for ADAS software, addressing memory leak issues and ensuring system stability during prolonged operations.

Master of Science Computer Visualistics

Bachelor of Science Computer Science

IT Management System v2

Developed an IT management system with a data lake architecture and internal data management capabilities to create a full dynamic CRM-based web app.

• Architected a scalable data lake using Directus with PostgreSQL as the central repository for all customer and product data.
• Integrated Steampipe to virtualize external data sources (APIs, cloud services) as queryable database tables within the data model.
• Deployed and managed the entire infrastructure using Dokploy for container orchestration and cluster management.
• Designed a unified GraphQL API leveraging graphql-mesh to abstract both internal (Directus) and external (Steampipe) data sources.
• Implemented role-based access control (RBAC) and data governance policies across the data lake.
• Optimized database query performance through indexing strategies and connection pooling.
• Automated data synchronization and ETL processes between external systems and the central Directus repository.
• Created comprehensive data transformation pipelines to normalize and enrich external API data before storage.
• Established monitoring and alerting for data integrity, API availability, and cluster health using Dokploy dashboards.
• Enabled self-service data management capabilities for non-technical users through Directus' intuitive interface.

Stack: Directus, Steampipe, Dokploy, GraphQL, graphql-mesh, TypeScript, PostgreSQL, Postgres Foreign Data Wrappers, ETL, RBAC, Data Governance, GitHub Actions, Docker, Git, Shell, Docker Compose, Docker Stack, Docker Swarm, GitHub Copilot, OpenCode, OpenSpec, devenv, nix

HR Data Compliance App

Creation of the HR Data Compliance application from the ground up.

• Designed and developed the complete Fullstack application from the ground up, prioritizing future scalability, comprehensive testing, extensibility, and long-term maintainability.
• Established a streamlined management process enabling clients to efficiently administer the application and manage data with minimal complexity.
• Built a dynamic application capable of fetching external API data and validating compliance through customizable user scripts.
• Implemented a database-first architecture that serves as the single source of truth for both API and UI components, eliminating the need for redundant type definitions.
• Architected a model-driven, type-safe system ensuring robust maintenance workflows and seamless feature expansion.
• Created an intuitive user interface leveraging shadcn/vue components for optimal user experience.
• Implemented a comprehensive CI/CD pipeline encompassing automated testing, building, and deployment through GitHub Actions and Terraform/OpenTofu infrastructure management.

Stack: TypeScript, Astro, Vue, shadcn/vue, vee-validate, Zod, drizzle-orm, Tailwind CSS, Supabase, PostgreSQL, Vite, Playwright, Vitest, GitHub Actions, Terraform, Docker, devenv, nix, Git, Shell, Docker Compose, GitHub Copilot, OpenCode, OpenSpec, devenv, nix

Voicedrop Shopify Theme Extension

Creation of a Shopify Theme Extension to enable Voicedrop inside of Shopify Stores.

• Created the full Shopify Theme Extension of the Voicedrop product for Shopify.
• Automated QA including Unit and E2E Testing including visual regression tests to meet the requirements of the Shopify guidelines.
• Led the release of the extension through the Shopify review process and aligned the guidelines to the product.
• Created the Shopify Theme Extension with a Remix proxy to route to the original Voicedrop instances, reducing the need for a second software stack.
• Increased UI/UX of Voicedrop to fulfill the requirements of the Shopify Guidelines.

Stack: TypeScript, Liquid, Nuxt 3, Vue, DaisyUI, Supabase, PostgreSQL, Vite, Playwright, Storybook, Vitest, Shopify, GitHub Actions, devenv, nix, Git, Shell, GitHub Copilot, OpenCode, OpenSpec, devenv, nix

Siemens Internal References

Migration of Siemens internal references app from monolithic server to edge computing.

• Migration of monolithic legacy server code to AWS Lambda functions.
• Development of new features and bugfixes for the legacy codebase.
• Integration of AWS Lambda functions for the new features.
• Implemented backend logic using Express.js within AWS Lambda functions (TypeScript).
• Configured and maintained GitLab CI pipelines and custom GitLab Runners for automated testing and deployment.
• Performed IP/Network error analysis within the AWS VPC environment to ensure microservice connectivity.
• Created a reusable 'AI writing assistant and lecturer' component, which was adopted by the Siemens ecosystem.
• Increased performance of the Excel export feature from minutes to seconds.
• Minimal invasive implementation of new features into the legacy code.
• Added comprehensive testing for new and existing code using xUnit and Moq.

Stack: AWS Lambda, AWS S3, AWS Bedrock, AWS DynamoDB, AWS API Gateway, AWS CloudFormation, AWS CloudWatch, C#, TypeScript, React, Next.js, Express.js, LangChain, xUnit, Moq, Terraform, Docker, GitLab CI/CD, GitLab Runner, XML, XPath2, Context Engineering, LLM-Integration, Prompt Optimization, RAG-Pipelines, Vector Stores, REST, Git, Shell, Docker Compose, GitHub Copilot

IT Management System

Developed an IT management system to streamline data management processes and improve functionality and reliability.

• Identified inefficiencies with Microsoft SharePoint for customer data management.
• Implemented Power Automate flow to automate fetching, processing, and integrating customer data into SharePoint lists.
• Addressed challenges like manual data entry, synchronization issues, and lack of scalability.
• Developed a customer replication using the views framework and Guilds GraphQL framework hosted on Cloudflare CI/CD pipelines.
• Utilized VueJS and Nuxt3 for web application development.
• Integrated continuous deployment into the GitHub repository using GitHub Actions.
• Created an OAS schema from the Atera API using graphql-mesh for a unified data schema in the web application.
• Streamlined data management processes.
• Freed up valuable time through automation.
• Established a unified data schema for accessing external third-party APIs in the web application.

Stack: Microsoft SharePoint, Power Automate, Vue, Nuxt 3, GraphQL, graphql-mesh, TypeScript, Supabase, PostgreSQL, GitHub Actions, Git, Shell, GitHub Copilot

Livil Flags App

Message aggregation and assistant app for in-car and mobile usage.

• Spearheaded the development of the Livil Flags App's end-to-end encryption system for robust user privacy and security.
• Crafted a custom voice assistant, enabling seamless execution of complex tasks through natural voice commands, significantly enhancing user engagement.
• Designed an engaging user interface for both in-car and mobile app environments, leveraging Jetpack Compose for a streamlined and consistent user experience.
• Contributed significantly to the technical architecture, incorporating Kotlin with Coroutines, Jetpack Compose, and HILT.
• Implemented sharing and validation processes using Firebase Firestore for secure data management.
• Revolutionized user experience through the custom voice assistant, leading to increased user engagement and satisfaction.
• Ensured seamless integration of core functionalities from the mobile app into the in-car environment.
• Designed a key exchange protocol based on the customer's pairing idea, ensuring secure data exchange with built-in encryption.

Stack: Android, Android Automotive OS, Kotlin, Coroutines, Jetpack Compose, HILT, Firebase, Firestore, TypeScript, Node.js, Cloud Functions, GitHub Actions, Git, Shell, GitHub Copilot

Bar Webpage with Google Sheets Integration

A webpage for a bar with a menu, store and contact form. The menu is managed through Google Sheets and the contact form and store is managed through Wix.com.

• Developed a highly customizable webpage for a top-class restaurant.
• Migrated and enhanced the structure of the old webpage using Wix.
• Implemented messaging, payment, shop, and content management systems.
• Customized content management system for drinks and food menus.
• Enhanced user engagement through a personalized webpage approach.
• Enabled easy manual updates of menus using a custom Google Sheets script.
• Facilitated seamless sharing of menu information with third-party providers.
• Empowered non-technical users to update webpage content without manual intervention.

Stack: Wix, Google Sheets, Google Apps Script

Product Manager for Wireless EMS System

Product Manager for Wireless EMS System

Managed hardware, firmware, Android and iOS mobile apps, and Google Firebase-based cloud infrastructure for world-leading wireless EMS System. Successfully managed a 15-member team, adapting and extending Scrum for various needs.

• Managed hardware, firmware, Android and iOS mobile apps, and Google Firebase-based cloud infrastructure.
• Successfully managed various stakeholders, including the Development Team.
• Ensured synchronization for the Tecnatives System development.
• Aligned diverse teams using Scrum, later adapted for specific team needs.
• Implemented extended Scrum for hardware team flexibility and time management.
• Designed software Scrum processes to meet team requirements without compromising overall quality.
• Prioritized comprehensive quality assurance, continuous integration, and continuous delivery for firmware development.
• Integrated Flutter SDK for mobile development, connecting backend and web application components under a single team.
• Implemented extended Scrum for hardware team, allowing for flexibility and time management.
• Ensured seamless integration of team contributions, enabling weekly to monthly feature delivery.

Stack: Scrum, Jira, Confluence

Flutter App for iOS and Android

Flutter App for iOS and Android

Spearheaded Flutter framework adoption for mobile development. Customized UI to fulfill special requests, ensuring user satisfaction. Managed store pages and app store listings, optimizing customer engagement.

• Spearheaded Flutter framework adoption for mobile development.
• Customized UI to fulfill special requests, ensuring user satisfaction.
• Implemented and maintained custom microservices for cloud connectivity.
• Managed store pages and app store listings, optimizing customer engagement.
• Developed a unified mobile app for Android and iOS with a single codebase.
• Successfully implemented real-time Bluetooth connection to hardware.
• Integrated and bridged C-based Bluetooth library without modifications.
• Established quality assurance with unit and integration testing.
• Automated alpha and production releases, enhancing efficiency.

Stack: Dart, Flutter, iOS, Objective-C, Swift, Android, Java, C, C++, GitLab CI/CD

Web App for License and User Management

Web App for License and User Management

Led the development of a global product management and license system for sales representatives. Successfully deployed the application across diverse environments worldwide.

• Built the initial backend architecture using Express.js, which was later ported to Firebase without changing the base architecture.
• Led the development of a global product management and license system for sales representatives.
• Successfully deployed the application across diverse environments worldwide.
• Spearheaded the project, showcasing expertise in Vue.js for rapid prototyping.
• Utilized TypeScript to enhance code quality and improve development efficiency.
• Implemented industry-leading testing frameworks, Jest and Cypress, ensuring comprehensive unit testing and end-to-end testing.
• Demonstrated the ability to deliver high-quality solutions under tight deadlines.

Stack: Express.js, Vue, JavaScript, TypeScript, Jest, Cypress, GitLab CI/CD

Firebase Cloud for Product License Management

Firebase Cloud for Product License Management

Successfully migrated license management code to Firebase, ensuring seamless integration and improved global backend operations. Introduced cloud functions for enhanced security, maintainability, and scalability. Designed an optimized database schema.

• Successfully migrated license management code to Firebase, ensuring seamless integration and improved global backend operations.
• Introduced cloud functions for enhanced security, maintainability, and scalability.
• Designed an optimized database schema, optimizing performance, scalability, and data integrity.
• Spearheaded the migration process, analyzing codebase, identifying compatibility issues, and implementing necessary modifications.
• Pivotal role in implementing cloud functions to automate tasks, improve response times, and ensure backend resilience.
• Maintained focus on product stability during the entire migration, with meticulous planning, execution, and continuous monitoring.
• Actively contributed as the principal architect in designing the database schema.

Stack: Node.js, TypeScript, Firebase, Cloud Functions, Firestore, GitLab CI/CD

Embedded Firmware for EMS Devices

Embedded Firmware for EMS Devices

Developed a revised codebase crucial for the successful expansion to a broader range of embedded hardware and chips for Bluetooth-enabled EMS devices.

• Identified and addressed excessive Bluetooth chip command transmissions, significantly improving product quality and stability.
• Developed a revised codebase crucial for the successful expansion to a broader range of embedded hardware and chips.
• Contributed to the entire product lifecycle with a focus on firmware development.
• Collaborated with the team on migrating C libraries to structured C++ implementations for an organized and portable firmware codebase.
• Identified and resolved a critical bug related to excessive command transmissions by the Bluetooth chip, enhancing overall product quality and stability.

Stack: C, C++, Atmel, Bluetooth, GitLab CI/CD

Microservice Cloud for Worldwide Product Traffic

Microservice Cloud for Worldwide Product Traffic

Spearheaded the introduction of microservices architecture to handle concurrent users and high-volume data transfer. Utilized Go, Docker and Kubernetes for efficient deployment and orchestration.

• Implemented microservices architecture for a complex product.
• Addressed scalability and maintainability challenges effectively.
• Ensured efficient handling of increasing user traffic and large data volumes.
• Managed Docker container networking and IP traffic analysis for distributed services.
• Spearheaded the introduction of microservices architecture.
• Utilized Go and Kubernetes for efficient deployment and orchestration.
• Selected MongoDB as the database for scalability and data management.

Stack: Go, Docker, Kubernetes, MongoDB, GitLab CI/CD

Unreal Engine VR App to Showcase EMS Suit

Unreal Engine VR App to Showcase EMS Suit

Developed a virtual reality demo using Unreal Engine 4 and C/C++ to showcase an electrical muscle stimulation (EMS) suit. Integrated Bluetooth technology to communicate with the EMS suit via an iOS device.

• Developed prototype solo within five days.
• Achieved seamless user experience through iOS integration and Bluetooth signaling to initiate EMS stimulation.
• Independently designed and implemented the entire virtual reality demo.
• Integrated Bluetooth technology for EMS suit communication.
• Ensured deployment on iOS devices for user accessibility.

Stack: Unreal Engine 4, C, C++, Bluetooth, iOS, GitLab CI/CD

Native iOS App for EMS Training

Native iOS App for EMS Training

Led the development of the iOS app, implementing Bluetooth communication and custom UI elements.

• Successfully led the iOS app development, implementing Bluetooth communication.
• Established a semi-automated release workflow for alpha, beta, and production stages.
• Led the implementation of the mobile app on iOS.
• Introduced quality assurance measures with unit and integration testing.
• Managed App Store submission and created product page content.

Stack: Objective-C, Bluetooth, iOS, Custom UI