SnapMail was developed by Eric Harris-Braun and Asher King in 1990 and it has been providing cross-platform, peer-to-peer messaging for the three decades since. Lighningrod Labs is now updating SnapMail using Holochain infrastructure for the next three.
Real-time simultanous editing of documents is perhaps the most important addition of the modern web. It's what makes Google Docs, Miro, and HackMD so much more productive and valuable to use than any singleplayer version of a similar app. Syn makes it indulgently easy for developers to build collaborative apps on Holochain. The Syn library and zomes do all the heavy lifiting.
Groups, especially remote colaborative groups, often lack contextual information about collaborators that makes working together harder. Co-locating oneself across a number of spaces in the context of a group (or groups) provides an important avenue for improving both sense-making and working together. Where provides a generalized grammar for creating shared maps for groups to see the emergent "whereness" of each other across those them, as well as the grammatics to self-evolved these spaces and how to represent "location" in them.
Explore the details in Where's github repo.