Offline-First App Architecture and Privacy by Design
How can an offline-first app support privacy and data minimization? A technical look at local processing, Privacy by Design, and AuraHarmony.
Reiner Ebel
Engineer in Industrial Electronics · Founder and developer of AuraHarmony
I am Reiner Ebel, an engineer in industrial electronics with an additional qualification in application development — and the developer of the frequency app AuraHarmony. Frequencies, sound and their effect on focus, relaxation and sleep have occupied me for years, professionally and privately.
What increasingly bothered me about the existing apps was that nearly all of them require a monthly subscription, many collect usage data along the way — and that trying out your own frequencies was practically impossible anywhere. So I built AuraHarmony myself: a one-time purchase instead of a subscription, fully offline, no account, with a free frequency generator from 1 to 20,000 Hz.
Coming from electronics shapes how I write about this subject. Oscillations, waveforms and measurement technology are my craft — so I verify rather than assert: I measured the app's frequency output with an oscilloscope and published the results in full, including the setup and the method. I am not a doctor or a scientist, however, and I do not pretend to be. That is why my articles consistently separate handed-down tradition, user reports and what is actually supported by evidence.
Verifiable facts
- Engineer in Industrial Electronics
- Additional qualification in application development
- Developer and publisher of the frequency app AuraHarmony for iOS and Android
- Own measurement series: the app's frequency output verified and documented with a Rigol oscilloscope
- Owner of the registered trademark AuraHarmony: DPMA 3020252526931
- Managing Director of EicDevCon UG (haftungsbeschränkt), Rosdorf (Imprint)
Articles by Reiner Ebel
4 min read
Solfeggio Frequencies List — All 9 Frequencies from 174 to 963 Hz
The complete list of all nine Solfeggio frequencies with their traditional meaning, an honest scientific assessment, and practical tips to get started.
6 min read
Binaural Beats, Solfeggio, 432 Hz, and Rife Compared
Binaural beats, Solfeggio frequencies, 432 Hz tuning, and Rife frequencies — what's the real difference, how do they work, and which one fits your day?
5 min read
Royal Raymond Rife and the CAFL List — A Beginner's Guide
Who was Royal Raymond Rife, and what is the CAFL list? The real history behind Rife frequencies — and how to use them safely for relaxation today.
4 min read
The Sound of Silence: How Medieval Monk Chants Help Us Unwind Today
An 11th-century monk's notation system quietly became the basis for Solfeggio frequencies — here's the real history, and how the science holds up today.
5 min read
Smartphone Frequencies on the Oscilloscope
Can smartphones reproduce clean sine waves? We measured our frequency app on a Rigol oscilloscope — both Solfeggio tones and binaural beats. Here is what we found.
3 min read
Why We Built AuraHarmony Without Accounts, Tracking, or Cloud
Every meditation app is collecting your data. We made a different choice — and here's why that mattered for the architecture.
3 min read
The Science of Binaural Beats — What Actually Happens in Your Brain
Two slightly different tones, one in each ear. Your brain hears a third tone that doesn't exist. Here's how that's possible.
3 min read
Understanding Solfeggio Frequencies — A Beginner's Guide
The nine sacred tones that may have shaped Western music — and what science actually says about them today.