Legal note & Data protection policy for the browser-extension Crossfoam


In the development of Crossfoam we strongly focused on data protection and privacy. Crossfoam itself does not collect and record any data. Only during the download of data from the corresponding social media services, we interact with servers of third parties. The respective data protection regulations of the corresponding services apply (see below). Furthermore, we have tried to keep the integration of so-called third-party software packages as small as possible. In order to exclude dangers at this level as well (see below for a list of packages).


Sebastian Meier & Daniel Lommes

Free & Open Source Software

The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, wheather in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

Software packages

D3 + D3-History

For the visualisations and interactive elements of the tool, the javascript library D3 is being used.


In order to also visualise larger networks, we need to make use of WebGL, the library REGL is helping us do so.


To communicate with Twitter and download network data, we use the library Twitter-Lite.

Network - Clusters

For detecting clusters / communities in the networks, we are using three different modules:


Mozilla has developed a module, that allows for cross-browser development of brwoser extensions.

Q (Promises)

In order for Crossfoam to work in older browsers, we included Q as a replacement for Promises.

Data collection

To collect network data, servers of social media service providers must be contacted. This only happens after explicit interaction of the user. Crossfoam does not perform this communication automatically. In addition, profile pictures of the accounts are loaded directly from the social media servers. This is also possible without being logged in to the respective service and having an account. Accordingly, data can also be collected through Twitter in this case.


For the communication with Twitter's servers, Twitter's data policies apply:

[Excerpt from Twitter's data protection policy] If you live in the United States or any other country outside of the European Union, EFTA States, or the United Kingdom, the data controller responsible for your personal data is Twitter, Inc. with an address of:

Twitter, Inc.
Attn: Privacy Policy Inquiry
1355 Market Street, Suite 900
San Francisco, CA 94103

If you live in the European Union, EFTA States, or the United Kingdom, the data controller is Twitter International Company, with an address of:

Twitter International Company
Attn: Data Protection Officer
One Cumberland Place, Fenian Street
Dublin 2, D02 AX07 IRELAND

Liability for Contents

As service providers, we are liable for own contents of this webextension according to Sec. 7, paragraph 1 German Telemedia Act (TMG). However, according to Sec. 8 to 10 German Telemedia Act (TMG), service providers are not obligated to permanently monitor submitted or stored information or to search for evidences that indicate illegal activities.

Legal obligations to removing information or to blocking the use of information remain unchallenged. In this case, liability is only possible at the time of knowledge about a specific violation of law. Illegal contents will be removed immediately at the time we get knowledge of them.

Liability for links

Our offer includes links to external third party websites. We have no influence on the contents of those websites, therefore we cannot guarantee for those contents. Providers or administrators of linked websites are always responsible for their own contents.

The linked websites had been checked for possible violations of law at the time of the establishment of the link. Illegal contents were not detected at the time of the linking. A permanent monitoring of the contents of linked websites cannot be imposed without reasonable indications that there has been a violation of law. Illegal links will be removed immediately at the time we get knowledge of them.


The underlying code is available under the open MIT license. The design of the application, including all graphics and texts are subject to German copyright law.