Digital preparedness
What happens to accounts, data and access when you are unavailable—and how families stay able to act.
Author · Engineer · Founder of 21 Fruits
Complex systems.
Clearly explained.
I write, teach and speak about digital preparedness, Bitcoin security and how technical responsibility can remain understandable and resilient across generations.
Technology earns trust when its assumptions, limits and evidence become understandable.
Book
The first book.
Book · In preparation
Das letzte Passwort
The first book by Felix Konstantin Brandt. Title, publication date and details will follow on the book page.
Articles
Writing about security, responsibility and what remains.
21 Fruits Insights · Series “Understanding Bitcoin”
Bitcoin in five minutes
What Bitcoin is and what it is not – explained simply, without jargon and without a sales pitch.
21 Fruits Insights · Bitcoin fundamentals
Bitcoin: strengths and open questions
21 Fruits Insights · Family and succession
The Recovery Governance Gap
21 Fruits Insights · Succession
The Successor Has the Title. Can the System Recover?
21 Fruits Insights · Verification
Verification Has Boundaries
Technical article · Werkstatt + Betrieb · 09/2019
Gut haftend und widerständig
Co-author of an article on low-temperature CVD, tool coatings and tool-life improvements in aluminium machining.
Podcasts, interviews & talks
A conversation partner for editors, podcasts and events.
Bitcoin without myths
Self-custody made understandable: control, responsibility and the practical limits of technical sovereignty.
Succession & family
Why authority is not access—and how recovery can be tested in advance.
Trust & evidence
What a system actually proves—and which uncertainty remains.
For editors and event organisers: please send interview, podcast, guest article and speaking requests to [email protected]. Short bio, topics and press photo in the press kit.
Teaching
From technical detail to a defensible decision.
Talks, seminars and workshops connect technical precision with clear mental models. The focus is on relationships: Which assumption supports a decision? Which evidence is missing? Where does a dependency begin?
University teaching: From 2019 to early 2026, teaching appointments at Albstadt-Sigmaringen University and Pforzheim University, focused on project management and cost accounting.
- Bitcoin security and self-custody
- Recovery, succession and keeping the family able to act
- Verification, trust boundaries and running your own infrastructure
- Technical decision and security processes
Company
Founder of 21 Fruits.
Bitcoin self-custody and family planning
21 Fruits
Designing self-custody, verifying recovery, preparing the family: 21 Fruits works with families so that their Bitcoin stays securely in their own hands today and the family can still act if something happens. 21 Fruits never holds Bitcoin and never signs transactions. Currently being built, with a small number of families in the DACH region.
Contact
For enquiries about the book, talks, podcasts and teaching.
[email protected] [email protected] Contact form X · @FelixBrandt_de