spigot is a calculating program. It supports the usual arithmetic operations, square and cube roots, trigonometric and exponential functions, and a few other special functions such as erf.

spigot differs from the average calculating program in that it is an exact real calculator. This means that it does not suffer from rounding errors; in principle, it can keep generating more and more digits of the number you asked for until it runs out of memory.

In particular, if you ask for a complex expression such as sin(sqrt(pi)), then most calculating systems would compute first pi, then sqrt(pi) and finally sin(sqrt(pi)), accumulating a rounding error at each step, so that the final result had a build-up of error and you would have to do some additional error analysis to decide how much of the output you could trust.

spigot, on the other hand, does not output any digit until it is sure that digit is correct, so if you ask for (say) 100 digits of sin(sqrt(pi)) then you can be sure they are the right 100 digits.

Apart from the Scheme compiler Chicken
 http://www.call-cc.org/
two other Scheme and one Forth system, there is
 MA, a minimalistic variant of the Acme editor, written in Tcl/Tk.

sshguard protects hosts from brute-force attacks against SSH and other services. It aggregates system logs and blocks repeat offenders using one of several firewall backends, including iptables, ipfw, and pf.

GNSS signal processing functions written in C
       Code generations
       Signal acquisition / tracking
       Decoding navigation messages
       Pseudo-range / carrier phase mesurements
   GUI application (AP) written in C++/CLI
   Visualization of GNSS signal processing in real-time
   Real-time positioning with RTKLIB (http://www.rtklib.com/)
   Observation data can be outputted in RINEX or RTCM format
   Support following signals (tracking and decoding navigation message)
       GPS L1CA
       GLONASS G1
       Galileo E1B
       BeiDou B1I
       QZSS L1CA/SAIF/LEX
       SBAS L1
   Support following front-ends for real-time positioning
       NSL Stereo http://www.nsl.eu.com/primo.html
       SiGe GN3S sampler v2/v3 https://www.sparkfun.com/products/10981
       Nuand BladeRF http://nuand.com/
       RTL-SDR http://sdr.osmocom.org/trac/wiki/rtl-sdr
   Support RF binary file for post processing

Mentioned on https://www.rtl-sdr.com/receiving-gps-with-an-rtl-sdr-dongle-and-gps-antenna/

A GNU implementation of the Secure Shell protocols

lsh is a free implementation (in the GNU sense) of the ssh version 2 protocol, standardised by the IETF SECSH working group.

Has a number of interesting articles, for example

Trying to find the DSLWP-B crash site, calculation of the impact location of the DSLWP-B spacecraft.
https://destevez.net/2019/08/trying-to-find-the-dslwp-b-crash-site/#more-7025

Detailed description of decoding telemetry from Voyager 1 received  2015-12-30 with the Green Bank radio telescope.
https://destevez.net/2021/09/decoding-voyager-1/
And some more recent data
https://destevez.net/2021/12/more-data-from-voyager-1/

Analysis of the Ephemeris quality during the Galileo outage in July 2019.
https://destevez.net/2019/09/ephemeris-quality-during-the-galileo-outage/
https://destevez.net/2019/08/galileo-outage-revisited/

Other articles related to satellite navigation
https://destevez.net/2022/03/a-rust-implementation-of-galileo-osnma/
https://destevez.net/2022/03/timing-sdr-recordings-with-gps/
https://destevez.net/2019/11/measuring-the-allan-deviation-of-a-gpsdo-with-an-sdr/
https://destevez.net/2023/10/update-on-the-galileo-gst-utc-anomaly/

The following articles contain information about the Pluto SDR
https://destevez.net/2023/02/maia-sdr/  Maia SDR, an open-source FPGA-based SDR project focusing on the ADALM Pluto. https://maia-sdr.org/
https://fosdem.org/2024/schedule/event/fosdem-2024-1841-maia-sdr-an-open-source-fpga-based-project-for-ad936x-zynq-radios/

https://destevez.net/2022/09/connecting-the-pluto-sdr-to-an-android-phone/
https://destevez.net/2022/08/calculating-the-qo-100-beacons-frequency-separation/

Details of the Reed-Solomon code used by Voyager
https://destevez.net/2021/12/voyager-1-and-reed-solomon/
https://destevez.net/2022/02/an-error-in-the-dsn-telecommunications-link-design-handbook-description-of-reed-solomon/

LDPC toolkit
https://destevez.net/2023/07/ldpc-toolbox-gets-ldpc-decoding/
https://github.com/daniestevez/ldpc-toolbox

List of RF recordings
https://destevez.net/rf-recordings/

Open source (MIT licensed), available for iOS, Android, Windows, OS X and Linux.

darktable is an open source photography workflow application and raw developer. A virtual lighttable and darkroom for photographers. It manages your digital negatives in a database, lets you view them through a zoomable lighttable and enables you to develop raw images and enhance them.

Available for Linux, FreeBSD and OS X.

stali is a brand new static linux distribution based on the original pre-2010 plans of the suckless.org project, but with a couple of revised goals:

stali goals
Follow the suckless philosophy
Target x86_64 and arm (RPi) support

Minisign is a dead simple tool to sign files and verify signatures.

It is portable, lightweight, and uses the highly secure Ed25519 public-key signature system.