Update September 7, 2016
As Thomas stated in the comments, the newest Version 0.11 of the plugin now implements the OpenGraph metatags wich are used by Facebook, Twitter Cards and other social networks. In the settings there is a new parameter "Fallback Image" where you can set the
Also in an earlier update the possibility to use the Shariff Backend was added. With these feature you can show a counter number on the sharing buttons for several networks which shows how often the article was liked, shared or "plused" there. You can download the backend and store it on your webspace. Then you have to set the plugin parameter "Backend for sharecounter" to the path where you stored it. The default of that setting points to a backend which is hosted on a webspace of a serendipity community member. You can use this backend but if you want to make changes to the configuration or if you have perfomance issues it is necessary to use your own. If you don't want sharecounters at all just set the parameter to "none".
Update June 22, 2016
The plugin provides all services that are shipped with Shariff. If you want more services to be supported you can get in contact with the Shariff project on Github. If they update their tool it will be implemented in the plugin periodically.
Original Article from June 22, 2016
Sharing is caring. To help your readers to share your blogposts with several social networks and other services there is a new Serendipity plugin called "Share Buttons" (serendipity_event_social). This plugin will add some share buttons for the networks and services you choose in the configuration of the plugin.
The plugin uses the free tool Shariff which is provided by the german computer magazin c't. This tool cares about the strong data protection laws in Germany an the EU. So there is no data transfered to the external sites until you click on the buttons.
The following services are supported for the moment:
And this is how it can show up in your blog:
You can also see the plugin working live here in this blog.
So if you wish to allow your readers to easily share your posts, install "Share Buttons" and give it a try. It is available via Spartacus. If you find some bugs or have some suggestions to the developers, feel free to give feedback at the user forum.