Private

EdgeNums, the tricky number puzzle

2026

A number puzzle for Android, iOS, Windows and the browser: one C# codebase, one Avalonia UI and four small platform projects on top. Every puzzle is checked before release, because the same deduction rules that generate the hints also prove that it can be solved by logic alone. The hint button names the rule that currently applies instead of revealing a cell.

edgenums.de →Read more

Technologies: .NET 10 · Avalonia · C# · WebAssembly · Android · iOS

Kickbase Kaderplaner

2022 – 2026

A squad planner for the Bundesliga fantasy game Kickbase. It answers one question: which players to sell, and what is left on the account afterwards. It searches the best eleven across all ten legal formations and shows what a sale costs, including the loss on the credit line. It started in 2022 as a Google Apps Script bound to a spreadsheet and now runs in the browser without any server.

kaderplaner.de →Read more

Technologies: TypeScript · Cloudflare · Google Apps Script

Doc2Lib SlotWatch App

2024 – 2026

Watches Doctolib once a minute for appointments opening up in a specialty near a location, and reports a hit right away over Telegram and mail with a booking link. Several search jobs run in parallel, with lockout periods and backoff per doctor, and a PWA interface for the phone with a setup wizard. One instance per person, because appointment search touches health data. For private use only. A Google Apps Script bound to a spreadsheet came first.

Technologies: JavaScript · Cloudflare Workers · D1 · Cron Triggers · PWA · Telegram Bot API · Resend · Geoapify · Google Apps Script · GitHub Actions

Secured List App

2022

A password manager built as a Flutter prototype in Dart, running on Android, iOS, web and Windows from one codebase. The data is encrypted with AES, and the key comes from a passphrase the user enters. Entries are stored either on the device or in Google Drive, so a backup does not need a service of my own.

Technologies: Flutter · Dart · AES encryption · Google Drive API

Stock Quote Add-In for Excel

2007 – 2018

Microsoft once shipped the MSN MoneyCentral Stock Quotes Add-In for Excel, and then it was gone. My add-in is the replacement. It brings stock quotes and FX rates into a worksheet as normal Excel functions, built on the Excel-DNA library. It worked from Excel 2007 through to Excel 2016 and stayed open source the whole time. It is no longer active, because Google shut down the service it pulled the quotes from.

Download on GitHub →Read more

Technologies: .NET · C# · Excel-DNA · Office development