Prismo

 Prismo  is open source link sharing software that supports microformats2 & Webmentions, and that used to also have a free service instance.

Features

 * Prismo users can be followed by Prismo users and by other ActivityPub software users.
 * Standards
 * microformats2
 * Webmentions
 * partial ActivityPub federation. Federation between different Prismo instances is still in development.

Open Source

 * https://gitlab.com/prismosuite/prismo

History

 * 2019-01-06 added microformats2 support:
 * 2019-04-25 added webmentions support:
 * https://prismo.news/ was the original Flagship Instance but the domain appears to be unresponsive (2020)
 * The original flagship instance suffered data loss and the lead dev decided to start a new instance on a different domain to avoid account hijacking.
 * https://prismo.xyz was the New Flagship Instance but appears to be have been squatted by blog spammers in 2020.