Found via https://pirsquared.org/blog/, where I followed a link to the sad, but interesting story of the Xfree fork to X.org.
http://asterisk.dynevor.org/xfree-forked.html
I have not read
https://matthew-brett.github.io/curious-git/
yet, but it sounds interesting.

LambdaNative is an open-source (BSD licensed) cross-platform development environment written in Scheme (Gambit-C), supporting Android, iOS, BlackBerry 10, OS X, Linux, Windows, OpenBSD, and NetBSD. Some cross-compiler support for Raspberry Pi (Carlson-Minot) and OpenWrt (Sitara) also exists. See also https://www.lambdanative.org/

This package provides a library and a command-line tool named wormhole, which makes it possible to get arbitrary-sized files and directories (or short pieces of text) from one computer to another. The two endpoints are identified by using identical “wormhole codes”: in general, the sending machine generates and displays the code, which must then be typed into the receiving machine.

The codes are short and human-pronounceable, using a phonetically-distinct wordlist. The receiving side offers tab-completion on the codewords, so usually only a few characters must be typed. Wormhole codes are single-use and do not need to be memorized.

Open-source hard- and software for two-factor authentication.
I need to test them and want to understand the differences between versions 1 and 2. The articles
https://solokeys.com/blogs/news/trussed-announcement and
https://github.com/trussed-dev/trussed-totp-pc-tutorial look interesting.

Delta provides language syntax-highlighting, within-line insertion/deletion detection, and restructured diff output for git on the command line.
Found via https://tecosaur.github.io/emacs-config/config.html
There are other programs using the name delta, for example
https://guix.gnu.org/packages/delta-2006.08.03/
"Delta assists you in minimizing "interesting" files subject to a test of their interestingness."

Gqrx is an open source software defined radio receiver (SDR) powered by the GNU Radio and the Qt graphical toolkit.

Found via the Fossil forum https://fossil-scm.org/forum/forumpost/168b2bb05e

Wiki about the Slice media Player. Last updated 2015-11.

Solid (https://solid.mit.edu/)  was created by the inventor of the World Wide Web, Sir Tim Berners-Lee. Its mission is to reshape the web as we know it. Solid will foster a new breed of applications with capabilities above and beyond anything that exists today.

Solid (derived from "social linked data") is a proposed set of conventions and tools for building decentralized social applications based on Linked Data principles. Solid is modular and extensible and it relies as much as possible on existing W3C standards and protocols.

https://solid.inrupt.com/how-it-works
Within the Solid ecosystem, you decide where you store your data. Photos you take, comments you write, contacts in your address book, calendar events, how many miles you run each day from your fitness tracker… they’re all stored in your Solid POD. This Solid POD can be in your house or workplace, or with an online Solid POD provider of your choice. Since you own your data, you’re free to move it at any time, without interruption of service.

gphoto-sync is an open source command-line tool written in Python. It’s purpose is to backup Google Photos and Albums using the Google Photos Library API. Once setup, it can be run on a regular basis, to ensure all the pictures stored in the cloud are also stored locally on your own storage.