Crowdflow started in April 2011 after it was revealed that iPhones collect and store their location data. We have since collected and analyzed the log files of almost 1.500 iPhones and iPads and created an open database of wifi and cell networks. We also visualized how these networks are distributed all over the world.

How Crowdflow started

After the tracking and collection of location data was revealed, Michael Kreil used the data stored in his iPhone and created the first heatmap. He then created a second heatmap with the information from the consolidated.db-files Bastian Greshake published. The next idea was to combine and analyze the data. A comparison between the time and location stamps revealed that Kreil and Greshake had almost met each other twice during the 10 months of recording. Obviously, log files from the iPhones could reveal a lot more than just location data, once several sets were taken into account. The only question was: just how much?

So on a sunday evening in April the idea of Crowdflow was born. On monday the blog was set up, a java application and the upload form prgrammed. After everything was uploaded onto the server, Crowdflow went online on tuesday – after just two days. Within the first 24 hours six sets of log files were donated. Over the next days the number went up, due to several media outlets and blogs who reported about the project.

On the 4th of May Apple released the iOS Update 4.3.3 that prevents the backup of log files to the hard drive. By mid-May (presumably when the last iPhones were updated), donations wound down. Since then the Crowdlow moved to a smaller server and data upload has been disabled. Almost 1.500 sets of log files had been collected.

How Crowdflow works

Owners of iPhones were asked to anonymously donate their location data. In order to do so they could download a java applet to extract the log files from the iTunes backup into one database. The database could then be uploaded to the crowdflow server. All the donated databases were combined, sanitized and analyzed. The name crowdflow refers to the use of crowdsourcing.

From the log files, we created an open database of known wifi and cell networks (which, in turn, are not necessarily open). We also visualized where the networks are located all over the world. But the possibilities don’t stop there: We have also visualized how iPhones scan for wifi and cell networks, as well as the downloading of new maps when traveling.

Even though no more log files can be donated, we still continue to explore the data and look for new insights.

Crowdflow in the news

Crowdflow has been featured on engadget, GigaOM and tuaw. Read an interview with Michael Kreil on Deutsche Welle.

Frequently asked questions

Will you give me your raw data?

No, you can only get the data released on this site.

Can I still contribute?

Unfortunately not. Since the release of iOS 4.3.3 in May 2011 the log files are no longer backed up to iTunes and the cache size has been reduced to a few weeks instead of months.