Spending some time to find informations about my gsoc project, i have heard about a project (promoted by google) to bring a common API for contacts sharing around web services : http://portablecontacts.net/ . There is also a document that list the services using the API : http://wiki.portablecontacts.net/w/page/17776143/Software-and-Services-using-Portable-Contacts The standard use OAuth, that is available via a small c library called liboauth, it depends from openssl and NSS and is released under MIT license, using this library could be easy to create a c++ wrapper and include it in the services kit. OpenSocial support the read only part of the Portable Contacts API. What about change the "google contacts addon" in my gsoc project for a "portable contacts addon"? It will bring support for google contacts as well as some other services (and presumably more in future). Regards