Goldstein

Goldstein is a Linux desktop application for encrypted conversation and file exchange between correspondents. It joins two functions that are often split across separate programs: a message window for back-and-forth text, and a transfer channel for handing over documents, images, or archives to the person on the other end, with encryption applied to what passes between the two sides.

The program is published by Mark J. Skinner under the GPL-2.0-only license, so the source may be read, modified, and redistributed under those same terms, and the cryptographic implementation is open to inspection by anyone willing to work through it.

Packaging is limited to Linux; no Windows or macOS build is recorded here, so a mixed-platform group would need something else for the remaining machines. This entry also does not state which protocol, key-exchange method, or server arrangement Goldstein depends on, nor whether it speaks to other chat networks — questions to settle from the project's own documentation before committing to it.