Screen calculator
Physical size in cm, pixel density (PPI), dot pitch and aspect ratio from resolution and diagonal, with saveable screens for comparison.
OpenTools
Small utilities I use myself. The card games run directly in the browser and can also open a private online table when you want to play with friends.
All tools
Kartenspiele
Schafkopf, Skat and Mahjong against bots or at a private online table with friends, plus scorepads for Schafkopf, Skat and Wizard. Rules for every game, explained with animations (in German).
Open Rules and overviewNoten lernen
Klaviertrainer für ein USB-MIDI-Keyboard: Noten im Notensystem lesen und spielen, von fünf Tönen um das mittlere C bis zu Menuetten von Bach, mit berechnetem Fingersatz und Vollbild fürs Tablet.
OpenRegex playground
Build regular expressions from examples and building blocks, test them with live match highlighting, and get every part of the pattern explained in plain English.
Open