It's your data!
Your data should be yours. OwnTracks does all it can to ensure that, and you decide where you store your data, how to process it, and for how long you store it (if at all).
However, be advised, that if you're very concerned about privacy, you probably shouldn't be using a smartphone at all. OwnTracks uses your smartphone's location services to determine where it is. While you decide whether you want to enable or disable this feature (check your phone's documentation), there is no guarantee that the APIs used by OwnTracks won't submit your data to the vendor's servers.
For example, it's quite possible that Apple or Google keep requests used for reverse geo-coding your location; there is pretty much nothing OwnTracks can do to avoid this.
As one of the developers writes:
We could, with great sacrifices to code complexity, battery efficiency and performance code around all native services offered by the platform in order to use third party maps and geo coders. In that case Google might not receive your geocoder requests but another third party that sells it. We could also work around the Play Services by handling all the location acquiring the old way by querying the GPS/WIFI/Cell positioning ourselves. I however doubt that these information isn't sent to Google in that case too. The thing is, if you don't want Google or Apple to collect your position you have to disable location services in which case you don't have to bother installing the app anyway.
It's your choice.
Like most website operators, OwnTracks collects non-personally-identifying information of the sort that web browsers and servers typically make available, such as the browser type, language preference, referring site, and the date and time of each visitor request. OwnTracks' purpose in collecting non-personally identifying information is to better understand how OwnTracks' visitors use its website. From time to time, OwnTracks may release non-personally-identifying information in the aggregate, e.g., by publishing a report on trends in the usage of its website.
OwnTracks also collects potentially personally-identifying information like Internet Protocol (IP) addresses for logged in users and for users leaving comments on OwnTracks' Web sites. OwnTracks only discloses logged in user and commenter IP addresses under the same circumstances that it uses and discloses personally-identifying information as described below.
Gathering of Personally-Identifying Information
Certain visitors to OwnTracks' websites and servers choose to interact with OwnTracks in ways that require OwnTracks to gather personally-identifying information. The amount and type of information that OwnTracks gathers depends on the nature of the interaction. Those who engage in transactions with OwnTracks are asked to provide additional information, including as necessary the personal and financial information required to process those transactions. In each case, OwnTracks collects such information only insofar as is necessary or appropriate to fulfill the purpose of the visitor’s interaction with OwnTracks. OwnTracks does not disclose personally-identifying information other than as described below. And visitors can always refuse to supply personally-identifying information, with the caveat that it may prevent them from engaging in certain website-related activities.
OwnTracks collects personally-identifying information in the form of location reports made by OwnTracks' apps which use OwnTracks servers. This information may be stored in order to make it available to OwnTracks' users.
OwnTracks may collect statistics about the behavior of visitors to its websites. OwnTracks may display this information publicly or provide it to others. However, OwnTracks does not disclose personally-identifying information other than as described below.
Protection of Certain Personally-Identifying Information
OwnTracks discloses potentially personally-identifying and personally-identifying information only to those of its employees, contractors and affiliated organizations that (i) need to know that information in order to process it on OwnTracks’s behalf or to provide services available at OwnTracks’s websites, and (ii) that have agreed not to disclose it to others. Some of those employees, contractors and affiliated organizations may be located outside of your home country; by using OwnTracks’s websites and servers, you consent to the transfer of such information to them. OwnTracks will not rent or sell potentially personally-identifying and personally-identifying information to anyone. Other than to its employees, contractors and affiliated organizations, as described above, OwnTracks discloses potentially personally-identifying and personally-identifying information only in response to a subpoena, court order or other governmental request, or when OwnTracks believes in good faith that disclosure is reasonably necessary to protect the property or rights of OwnTracks, third parties or the public at large. If you are a registered user of an OwnTracks website or service and have supplied your email address, OwnTracks may occasionally send you an email to tell you about new features, solicit your feedback, or just keep you up to date with what’s going on with OwnTracks and our products. We primarily use our various product blogs to communicate this type of information, so we expect to keep this type of email to a minimum. If you send us a request (for example via a support email or via one of our feedback mechanisms), we reserve the right to publish it in order to help us clarify or respond to your request or to help us support other users. OwnTracks takes all measures reasonably necessary to protect against the unauthorized access, use, alteration or destruction of potentially personally-identifying and personally-identifying information.
If OwnTracks, or substantially all of its assets, were acquired, or in the unlikely event that OwnTracks goes out of business or enters bankruptcy, user information would be one of the assets that is transferred or acquired by a third party. You acknowledge that such transfers may occur, and that any acquirer of OwnTracks may continue to use your personal information as set forth in this policy.