Software
Alongside my research I work part-time as a software developer at Auto-Koch GmbH & Co. KG. Over the past years my main project there has been KoKi, an in-house system for managing customer and vehicle data that I designed, built and continuously expanded, and which is in daily production use across the dealership’s branches. I develop KoKi mostly on my own, including about one and a half years as part of a two-person team. The source code is proprietary and not publicly available.
KoKi: Customer & Vehicle Management
All screenshots show synthetic test data.
KoKi is a web-based business application I have been developing since 2019 for the day-to-day operations of a car dealership group. It keeps customer and vehicle records together, supports the service workflow around inspections (TÜV) and maintenance, and automates the recurring communication and paperwork around them. The system is multi-tenant across the group’s five branches, manages tens of thousands of customers and vehicles and is used in production every day.
Key Features
- Combined customer and vehicle records, automatically reconciled with the DMS every week and on demand at the click of a button
- Automatic calculation of inspection and statutory roadworthiness (HU) dates; a decision graph shows how each date came about
- Vehicle row with hover cards: appointments, data protection and all of a customer's vehicles at a glance
- Data-protection consent on two levels (general and per brand)
- Appointment reminders and a notes calendar with reminders
- SMS, email and PDF from templates whose placeholders are filled from the customer data
- Internal chat for staff
- Role system and complete vehicle history
- Work overview and statistics (monthly trends, success rate, branch comparison)
Technical Highlights
- Custom single-page application in vanilla JavaScript, no front-end framework
- Real-time client-server architecture over WebSockets rather than a REST API, with all application logic server-side
- Live updates pushed via PostgreSQL LISTEN/NOTIFY triggers
- Regular automated synchronisation with the dealership management system
- Standalone background services for data sync and automated reminders
- Server-side PDF generation from templates using headless Chromium
- JWT-based authentication, bcrypt password hashing and role-based access control
- Parameterised SQL throughout (no ORM), guarding against SQL injection
- Traceable scheduling algorithm: every calculation is stored as a snapshot, and a cross-check test verifies the explanation shown in the browser against the calculation on the server.
- Automated quality assurance with a single command: a test database is rebuilt through the entire migration chain, with simulators for the DMS, workshop planning and SMS/email delivery, plus unit, database and browser tests in real Chromium.
- Every weekly sync run is logged with key figures and errors.
- AI-assisted development for several years, currently with Claude Code; every change is safeguarded by the automated tests.
Technologies
Frontend
HTML5
CSS3
JavaScript
Backend
Node.js
WebSocket
PostgreSQL
Tooling
Puppeteer
JWT & bcrypt
Vite
Handlebars
Vitest