Seldom without a computer of some sort since graduating from the University of British Columbia in 1978, I have been a full-time Linux user since 2005, a full-time Solaris and SunOS user from 1986 through 2005, and UNIX System V user before that.
On the technical side of things, I have spent a great deal of my career as a consultant, doing data analysis and visualization; especially spatial data analysis. I have a substantial amount of related programming experience, using C, awk, Java, Python, PostgreSQL, PostGIS and lately Groovy. I'm looking at Julia with great interest. I have also built a few desktop and web-based applications, primarily in Java and lately in Grails with lots of JavaScript on the front end and PostgreSQL as my database of choice.
Aside from that, I spend a considerable amount of time writing proposals, technical reports and - of course - stuff on https://www.opensource.com.
Authored Comments
Thanks for bringing Jami to our attention as an alternative, Tom.
Thanks for the comment, Jorge. It's a good question. I see that there is a Signal server published on Github
https://gist.github.com/aqnouch/9a371af0614f4fe706a951c2b97651e7
But I'm not clear if that's what Signal actually runs on their servers. nevertheless, it seems we can host our own Signal servers if / as required.
As to the others, I don't know.