Christian Tietze
Freelance trainer with hackers&wizards
Christian has run his own Mac and iOS app business since 2013. The Archive, his Zettelkasten app, has thousands of daily users and eight years of continuous releases, and alongside it he took the contracts where architecture was the problem: migrating Starface's enterprise VoIP client from AppKit to SwiftUI, building the integration layer behind Timing's automatic time tracking. His second trade is knowledge work. He has written in public since 2010, runs zettelkasten.de with Sascha Fast and built The Archive as the tool for it, two books and close to a thousand posts along the way: sixteen years of work on how a body of knowledge accumulates, stays navigable, and holds together as it grows. That turns out to be the skill agents expose. What is not written down does not exist for an agent, and deciding what to write, how to structure it and what to drop is a discipline most engineering teams never had to build. Six years as a peer tutor at Bielefeld University shaped how he runs a room, reflection questions over monologue, meeting people where they stand. He has run AI adoption workshops for manufacturers in Ostwestfalen, organizes the Claude Code Anonymous meetup in Bielefeld, and delivers Agentic Engineering for Developers and QA at hackers&wizards.
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