Engineer  ·  Builder  ·  Adventurer  ·  In that order, depending on the week

David Tatzel.

Software engineer and team leader. The belief that runs through everything I touch is older than any job, and bigger than software: anyone can do anything. Understand the problem. Break it into pieces you can face. Take the first one — then the next.

30+
Years Building
5
U.S. Patents
2
Apps Shipping
How I work What I've built
§ 00 — Marginalia : "Read the manual. Do the work."

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§ 01Operating Principle

Anyone can do anything.

It started with screws. Whatever I could open as a kid — radios, the lawnmower, anything with a back panel — I'd take apart, lay the parts out on the floor, and work out how to fit it all back together. Some of it didn't fit on the way back. I learned from that too. The lesson stuck: every system, no matter how alien at first, is a stack of parts someone built and someone else can rebuild.

Forty-plus years on, I apply the same trick to everything. Figure out what the problem actually is. Break it into pieces small enough to be honestly faced. Solve each one. Reassemble. The medium changes — software, hardware, a microgrid, a bad week, a good team, a service panel, a transmission, a kid's hard question — but the discipline does not.

I want engineers and friends around me who may not yet know the answer but won't flinch from finding it. That stance has built my career, the team I lead at Savant, and the apps I ship on weekends. It also gets the dishwasher fixed.

▲   The current toolkit

Good people. Sharp tools. Engineering as guardrails.

My job — at Savant, and on side-projects too — is to put a strong team in front of the best available tools, then get out of the way. The leader's work is the conditions, not the keystrokes. Hire people who'll grow into harder problems than they walked in with. Mentor them through the hard parts. Defend the work upward; pass the credit downward. Give them tooling that punches above its weight, and engineering principles loud enough to keep the leverage honest.

Agentic AI is the newest sharp tool in the box. I treat it like the rest — leverage, not magic. Claude Code in my editor sits next to the linter, the manual, and the colleague who'll push back on a bad PR. Each one earns its keep by accelerating correct work — not just any work.

The principles don't change. Read the diff. Test the change. Own the outcome. AI doesn't relieve a builder of judgment — it amplifies whichever judgment is already there. Sloppy taste produces sloppy output, faster. Good taste compresses years of work into months. Best people. Best tools. Engineering as guardrails. Repeat the recipe.

Your leadership style, coupled with your strong advocacy for your team, are significant reasons I have chosen to continue to work at Savant. Your mentorship is genuinely one of the most rewarding aspects of my role. — Software Engineer, Savant · 2023

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§ 02Career

Two companies. Thirty years. Plenty of shipped software.

Long tenures, on purpose. The deepest work happens after year five, not before. Both teams shipped products I'm proud to put my name beside.

2011 — Present  ·  14+ years
Sv

Savant Systems

Smart-home, energy, and embedded platforms.

Currently Executive Director, Embedded Platform Engineering. Joined as a senior engineer writing home-automation software on iOS, OS X, and embedded Linux; grew through technical manager, director, and energy/microgrid director roles. Today my teams own firmware, DevOps, embedded software, and the energy platform. The work has shipped some of the most ambitious products on the smart-home market — and earned the patents below.

Home Automation Embedded Linux Firmware Microgrid Controller iOS / OS X Team of 30+ Multi-Office
Savant.com → Patents →
1995 — 2011  ·  16 years
ES

Engineered Software

Mac CAD software with a long, loyal user base.

Joined out of high school as an intern. Left as Principal Engineer, leading R&D on the flagship product line. Shipped PowerCADD and PowerDraw across the Mac OS Classic → OS X arc, wrote the PowerDWG CAD interchange translator, ported modules to PowerPC, and built the company's online commerce. The product line outlived the era — users still rely on it today.

PowerCADD PowerDraw PowerDWG Mac OS / OS X PowerPC Port C/C++ / Objective-C Principal Engineer
PowerCADD → EngSW.com →

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§ 03Built & Shipping

Apps under my own name.

Side-projects that became real products. Both live in the App Store. Both started from real people in my life trying to do useful things — and not finding tools good enough to help.

LiftCortex app icon

LiftCortex

Plan blocks. Run split days. Stay locked in.

Started when my son Jonathan signed up for his first bodybuilding competition. He needed a real tool to plan splits, log sessions, hit macros, and count down to show day — so I built him one. Now in 11 languages, with a Smart Stack widget, shareable splits, iCloud sync, and a watchOS companion. No subscription, no account.

Workout Splits Macro Tracking Countdowns Apple Watch Smart Stack iCloud Sync 11 Languages
Download LiftCortex on the App Store Site → Deep dive →
MemberDex app icon

MemberDex

Branded member directory for any community.

Started from a conversation with my PT, Ashley Katzenback: managing her business-networking groups in iPhone Contacts was a mess — names lost in the same list as every plumber and friend. Three days later I sent her MemberDex v0.1. It grew into a white-label, multi-tenant directory platform for HOAs, faith groups, chambers, and professional networks. One iOS app, branded per-org. A web admin for member lifecycle, custom fields, billing, audit, and one-click backup. Built end-to-end: iOS, web admin, Go backend, Stripe billing, self-hosted ops.

Multi-Tenant iOS + Web Admin Custom Fields Bulk Import 2FA + Audit Log Backup / Restore Stripe Billing Offline Ready
Download MemberDex on the App Store Site → Deep dive →

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§ 04Patents & Research

Granted by the USPTO.

Five issued United States patents in home-automation user interfaces, multi-role automation devices, and wireless device provisioning — from work I led or contributed to at Savant. Plus two academic publications from research at UNC Greensboro.

US 9,306,763
Providing a user interface for devices of a home automation system
Apr 2016
US 9,323,239
Configuration interface for a programmable multimedia controller
Apr 2016
US 20,160,216,703
Configuration user interface for a home automation system
Jul 2016
US 8,972,858
Configuration interface for a programmable multimedia controller
Mar 2015
US 20,140,245,148
Video tiling
Aug 2014
US 20,200,267,013
Multi-role devices for automation environments
Aug 2020

Academic publications

User Modeling for Tailored Genomic e-Health Information — research assistantship, UMAP, July 2008. Co-author with Dr. Nancy L. Green.
Genetic Risk Education Using Interactive Graphics — co-author, UNC Greensboro. B.S. Computer Science, Mathematics minor; cum laude; Upsilon Pi Epsilon CS National Honor Society.

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§ 05Field Notes

Evidence-based guides I keep for myself.

I read a lot of medical literature for fun. These two reference documents are the boiled-down, fully-cited versions — open in your browser, zoom to taste, print if you must. Every claim is sourced. Nothing is sponsored.

Vol. I — Longevity

The Longevity Playbook

Thirty-nine evidence-ranked interventions for extending healthspan, plus fifteen harmful habits debunked. Hair, skin, eyesight, hearing — every claim cited.

24 beneficial 15 myths v3.0
Read the playbook
Vol. II — Supplementation

The Lifter's Supplement Encyclopedia

Sixty-five-plus supplements, ranked by evidence for strength athletes. Muscle, hormonal, joints, recovery, cognitive, anti-aging. Companion to the Playbook.

65 substances 9 categories S→F tier
Read the encyclopedia

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§ 06Practices

Four habits I've earned the hard way.

Not virtues to claim, just observations after thirty years of shipping. They survive contact with bad weeks.

i.
Show up
For the team, for the family, for the work. The boring superpower compounds.
ii.
Read the manual
Code, controllers, contracts, panels — every system is knowable to anyone willing to sit with it.
iii.
Defend the team
Heat goes up. Credit goes down. Advocate hard for the people doing the work.
iv.
Ship something
Patents, products, side-projects, pull requests. Make a thing real every chance you get.

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§ 07Kept

A note I keep in a drawer.

Handwritten, on actual paper, mailed across state lines. The metric I care about isn't titles or the patent count — it's whether the people I've worked with would choose to do it again.

“
You aren't just a great manager — you advocate for me, and not just for me but for the ones in the past as well. My longevity here is something I owe completely to you. Thank you for sticking up for me and my career through the hell that was the pandemic, the trials that were my college, and the open door that is my future.
Software Engineer, Savant SystemsHandwritten letter · April 2022

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§ 08The Stove

A second discipline.

The kitchen is where I practice the same thing in a different language. Weekend dinners, the grill, vegetarian remakes of the classics — equal parts art and science, run solo, judged by whether the people I love eat well. Mise en place. Read the recipe. Taste as you go. Ship a plate.

Giuliana, Jonathan, Alexis, my mom Terry — they're who the work is for. Four cats — Pumpkin, Ginger, Spooky, and Schweetie — handle quality assurance from the counter.