What Traces is, and how it started

Published in
2 min readSep 30, 2019


Traces is an app that records GPS coordinates and visualizes them on a single map. This enables you to know, where you have been and where not.

In a broader sense, Traces is also a software suite, which currently contains three software:

  1. Traces iOS: records and visualizes traces (a GPS track is called trace) on iOS devices (started in 2015)
  2. Traces Web: visualizes and manages traces (started in 2017)
  3. Traces Recorder iOS: records traces (started in 2018)

How it started

The idea of Traces can be traced back in the summer of 2014. At that time, I was studying in a French city called Rouen. I was truly attracted by the layout of the city and the aesthetics of the buildings. I wanted to see it all. I ran, biked and even took local buses to discovery different neighborhoods. But as I visited more places, I had a problem remembering them. There were many deja-vu moments. How could I know where I had visited? How could I plan running and bike routes that I’d never been before? I googled at first but didn’t find any usable tools. But I had a habit of running and biking with Strava on so I had a lot of GPX files. Could I overlay all those GPX files in a single map? With some research, I achieved that with Mapbox.

Early web version based on Mapbox in Nov 2014.
Early web version based on Mapbox in Nov 2014. Different colors signify different month of recording.

Looks good huh?

In 2015, I moved to Palaiseau in Grand Paris to start my internship at Peugeot. Palaiseau is around 25 KM from Paris center. On weekends, I would usually take the RER train to the city to explore the capital de la France!

Soon the web version become slow, laggy and painful. That was the moment I wanted to take a leap and start off an iOS project that handles better with performance and cuts the dependency on other GPX recording apps like Strava. After days of trying and hacking, Traces was up and running and eventually released on the App Store. The initial version was built with Swift 1.2, a very very early release of Swift.

This is basically the story behind the Traces.

At last, I’d like to present the current map view of Rouen.

Current Web version of Tracestrack in Rouen. Red lines are running and purple lines are cycling.