Retrace

A birth-time calculator that says plainly what it cannot do.

languages, right-to-left included: 51
differences between iOS and Android across every compared case: 0
documented birth times used to measure the method: 110

Store release pending

Retrace is for people who don't know their exact birth time. You enter a date, a place and the range the time may fall in, then the dates of events in your life. The app shows which times in that range your events touch most, and why.

It makes no claim to find your birth time. I measured the method on 110 cases with documented birth times, and it did not pick the real time better than chance. That result is published inside the app, and the product is built around it: a transparent calculator, not a prediction.

Underneath is a single C++17 core shared by two fully native apps, SwiftUI on iOS and Jetpack Compose on Android. Every calculation runs on the device, offline, with no account.

What is in it

01One C++17 calculation core shared by native SwiftUI and Jetpack Compose apps, checked for identical output on both platforms.
02A measurement pipeline against documented birth times, with a sealed validation set and success thresholds written down before testing.
03Planet and Chiron positions checked against NASA JPL data.
04Adaptive layouts for phones, iPad, Android tablets and foldables, in 51 languages with right-to-left support.