Our interview series with members of the geo community continues today with a chat with Jan-Piet Mens, one of the makers of OwnTracks, a software that allows people to track their location via a mobile app.

Here’s a screenshot of the OwnTracks server software, taken from the OwnTracks documentation. image

JP, many thanks for making the time to chat with us!

1. Who are you and what do you do? What is OwnTracks?

I am Jan-Piet (JP) Mens and I came up with the idea of OwnTracks, but there’s much more than just an idea. Christoph Krey is our tireless iOS mobile creator who completes implementing features before we’ve even finished thinking them up, Alexander Rust built the Android app and proved the original idea could be done, and Ben Jones is our home automation chap: he’s done wonders with OwnTracks and the openHAB home automation broker.

2. Why did you build OwnTracks? Who uses it, and why?

The idea for OwnTracks arose when I was fiddling with Google Latitude and heard it was to be put to rest. I was playing with the lightweight TCP-based MQTT protocol at the time and thought it’d be “trivial” to implement something similar to Latitude but a) make it speak MQTT and b) ensure the data could be used privately without a cloud service. Little did I know how much blood and perperspiration Alexander and Christoph would have to put into the mobile apps and how many thousands of kilometers I’d have to drive for tests.

We believe some of our users use OwnTracks to keep a record of where they’ve been, others use it to keep track of friends (who share a private MQTT broker or meanwhile also HTTP endpoint), and yet others use OwnTracks for home automation tasks. To be honest, we don’t really know who uses it and why – you use our Open Source apps with your own servers so we don’t get to see any of your data, and that’s fine: it’s the way we designed OwnTracks to be!

3. With GDPR only a few weeks away and all the recent news about Facebook, privacy is a hot topic. Has this been reflected with growth in the OwnTracks community?

OwnTracks was designed with privacy in mind. We strongly suggest to our users to host their backend at home using something as small as a Raspberry Pi or as a docker image on a small NAS server. (In fact we probably upset them when we tell them we won’t assist in getting them to run OwnTracks with public services!) We intentionally do not offer a platform other than our anonymous demo site. To put it bluntly, our users manage their own data.

4. Tell us about some of the technical challenges of making an open-source, location based service with clients for both iOS and Android and server software. Any advice for other developers in the location space?

Keeping the apps running on the current level of the operating system platforms is a nightmare. The platforms (especially the mobile platforms) evolve dramatically, introduce incompatible API changes. This is a lot of unpaid work, never ending and often frustrating. The sheer number of different operating systems and devices make this very tedious work, and testing is difficult; we rely on members of the community to tell us when things don’t work, which they typically do, sometimes not very nicely…

On the back-end side, we have umpteen different operating systems and versions, and users are very demanding: “where’s the package for this OS I run?!”.

5. A few weeks ago OpenCage was integrated into OwnTracks as an option for reverse geocoding (nice work!). The maps that locations are shown on though are still from a proprietary provider (Google). Any plans to integrate OSM based maps?

On the mobile platforms we decided to use the native map provides for iOS and Android to limit the scope. Anything else would cause even more work. We will entertain the thought of changing that, if we are helped in implementing such features. Server-side our “Recorder” can use OSM maps.

6. What is the most surprising use case of OwnTracks you have seen?

We once got an issue report to the effect that OwnTracks on iOS didn’t display the speed correctly at over 800 km/hour. It turned out that was a fighter pilot who worked at supersonic speeds. Christoph found and solved the issue, but we all got quite a thrill out of that use-case.

A second quite interesting example was somebody who wanted us to add barometric pressure readings to OwnTracks on iOS (iPhone 6 and higher can do that) in order to increase the accuracy of Pacific storm predictions by crowdsourcing the readings.

7. One of the great “features” of OwnTracks is the excellent documentation. As a tool used by developers, documentation is something we are continually focused on, but it can be a major challenge to explain complex technical matters in a simple way. Any advice for us?

Having a native speaker who has a “faible” (that’s not a native English word :-) for good documentation helps, and this particular author abhorrs bad documentation. Good documentation is vital for any project, and we hoped it would help our users if we invested time and effort in what we lovingly call our “Booklet”.

8. What’s next for the OwnTracks project? How can people get involved?

People can help us bring OwnTracks to more platforms, beta test and give us good ideas. They can also contribute code, documentation, and let’s be honest: a meal or two would be nice as well. We’d love for our users to tell us about their use-cases for OwnTracks: they should submit stories – that motivates us no end! Spread the word, tell your neighbours, colleagues, and bosses about the benefits of OwnTracks, Open Source in general, and those of a self hosted environment in particular! Pricacy is hugely important in this day and age!

Use OwnTracks for your projects, and hire us to get them implemented.

Congrats JP, to you and all the OwnTracks contributors on this wonderful project. We’re delighted that OpenCage could be integrated, and hope that it helps briong more attention to the benefits of open data. Hopefully this post helps get you more users, but also more contributors.

happy location tracking,


Please let us know if your community would like to be part of our interview series here on our blog. If you are or know of someone we should interview, please get in touch, we’re always looking to promote people doing interesting things with open geo data.