Selected work: software running in production.

Pass the DTZ — on the first attempt

A learning platform that realistically simulates the DTZ instead of just collecting material: 2,900+ words, grammar A1–B2, AI coaching and real exam tasks — free during beta.

• All four skills: listening, reading, writing, speaking
• AI conversation partner with 6 Azure neural voices
• Essay grading by photo or text, Leitner vocabulary

EU e-invoicing for the EN-16931 era

A platform that generates, validates, sends and archives EN-16931-compliant invoices in an audit-proof way — including DATEV export and EU localisation. Correctness is provable, not asserted.

• XRechnung & ZUGFeRD from one source, checked against the official schema
• Tax logic incl. reverse-charge (§13b) and small-business rules
• Audit-proof archive with a verifiable chain of record

Warehouse OS for small teams

A warehouse operating system a small team can run themselves: real-time stock, orders and IoT monitoring in one platform, shipped in 17 languages.

• Module-isolated architecture — features change without collateral damage
• Real-time stock & events over SignalR
• 17 languages out of the box, IoT monitoring built in

An AI agent that never sleeps

An autonomous AI agent as a product: it writes, publishes and reports — with a traceable history and an architecture that keeps load and cost in check.

• Disciplined LLM cycle instead of single prompt calls
• Background pipeline over Redis queues
• Controlled image & content generation

Configure windows, get quotes from vetted installers

A platform where several companies quote the exact same technical specification — customers compare price, lead time and scope, and contact details are released only after they decide.

• Server-side pricing engine on a real profile catalogue — instant indicative price
• Anonymised postcode-based lead routing + partner portal with offer workflow
• Specification PDF, Stripe payments, GDPR consents and legal documents

Made-to-measure windows — from survey to installation

Instead of “please call me back”, a complete window specification lands in the inbox — the company can price it straight away and the customer has a quote within 1–2 working days.

• Configurator with live preview — sashes, opening type, hinge side, glass, colour, size
• Enquiry without registration, with a clean GDPR consent
• Advisory content with real figures (Uw/Ug, frame depth, RC2) instead of marketing

AI avatar marketplace for video

A platform to find, order and receive AI avatars — with robust job processing instead of blocking requests.

• Asynchronous render pipeline over Celery
• Two-sided marketplace: creators & buyers
• Multiple AI models behind one abstraction

Family organisation for the DACH region

A family platform with web, iOS and Android clients, real-time updates and location features — daily organisation in one app.

• Canonical VSA — clean slices, not a monolith
• Real time over WebSocket, location over PostGIS
• Native iOS (SwiftUI) & Android (Compose) plus web

E-commerce platform with native apps

An e-commerce platform with web and native apps that handles regional delivery and ordering windows cleanly.

• Web plus native iOS & Android apps
• Delivery areas & time slots in the core
• Solid Laravel backend

AI financial audit for the DACH region

A platform that analyses financial documents with AI — with results a human can review and stand behind.

• Controlled LLM flow instead of a black box
• DACH focus & privacy by design
• Traceable analysis

TMS & fleet management for forwarders

A TMS platform for the DACH region that bundles around 20 modules — from dispatch to AI route planner — in one system, no third-party tools from day one.

• Around 20 modules in one product
• Routing & live positions over PostGIS
• AI route planner with live diesel prices

Understand any video, revoice it, publish it everywhere

A single link becomes finished, multilingual content for every channel in minutes. Cloud sync ties the web app to the iOS and Android clients.

• Pipeline from transcript to multi-platform post
• 6 languages, 5 AI providers, bring-your-own-key
• Stripe plus Apple/Google in-app billing

AI-assisted crypto trading platform

A production platform with a trading dashboard, admin panel and an eight-language landing page — secured with JWT, 2FA and encrypted exchange API keys.

• Multi-tenant real-time engine
• AI analysis with budget cap
• Binance integration over WebSocket

Manage and monetize Telegram groups

A production platform that unifies group moderation and paid memberships, with automatic access revocation and correct per-country VAT.

• Paid channel subscriptions via Telegram Stars & crypto
• EU VAT/OSS with VIES validation
• White-label agency mode & 2FA

100+ SEO and web tools under one roof

The platform kept running without downtime while PHP 7.4 and Apache were removed from the host. 100+ tools, the multilingual UI and subscription billing remain fully operational.

• 100+ SEO, PDF & image tools
• 11 languages, premium subscriptions
• Legacy safely containerized

Marketing automation for Messenger and Instagram

The platform runs stably and isolated on PHP 8.3 in production without pinning the rest of the server. Real-time chat via Pusher and Stripe/PayPal billing keep working unchanged.

• PHP 8.3 container, no code rewrite
• MariaDB over Unix socket, no open port
• Uploads and sessions persisted outside the image

Marketing site for an iOS strategy game

A standalone marketing site with game intro, NFT section and a hardened contact channel — live at buildinvest.online.

• Next.js 14 App Router, static and fully animated
• Custom contact API with honeypot, rate limit and SMTP
• Containerized, HTTPS, no page builder