OpenType text shaping engine

https://harfbuzz.github.io/

Anti-spam / denial of service counter-measure tool

http://www.hashcash.org/

Hierarchical Data Format library (from NCSA)

https://www.hdfgroup.org/

Portable and enhanced troff, nroff, and related utilities

https://n-t-roff.github.io/heirloom/doctools.html

Automatically generating simple manual pages from program output

https://www.gnu.org/software/help2man/

Online help viewer for GNUstep programs

http://www.roard.com/helpviewer/

Monospaced font for programmers by a programmer

https://pcaro.es/p/hermit/

Tiny program that sends some load to a web application

https://github.com/rakyll/hey

High-color icon theme shell from the FreeDesktop project

http://www.freedesktop.org/Standards/icon-theme-spec

Library to access USB HID-class devices

https://github.com/libusb/hidapi

Customizable syntax highlighter

http://www.andre-simon.de/

Framework needed by Project Manager

http://home.gna.org/pmanager/

Performance-portable, length-agnostic SIMD with runtime dispatch

https://github.com/google/highway

Stacking Wayland compositor with tiling capabilities

https://hikari.acmelabs.space

Minimalistic C client library for the Redis database

https://github.com/redis/hiredis

Hitori

https://wiki.gnome.org/Apps/Hitori

Split files into encrypted fragments

https://github.com/jesseduffield/horcrux

IEEE 802.11 AP, IEEE 802.1X/WPA/WPA2/EAP/RADIUS Authenticator

https://w1.fi/hostapd/

Small utility which displays the system activity in a very special way

http://dindinx.net/hotbabe/

Network auditing tool

http://www.hping.org/

Hebrew spellchecker and morphology engine

http://hspell.ivrix.org.il

All W3C published SGML DTDs for HTML

Converts HTML documents into plain text

http://www.mbayer.de/html2text/

Better top(1) - interactive process viewer

https://htop.dev/

Time synchronization over http utility

http://www.vervest.org/htp/

HTTP request/response parser written in C

https://github.com/nodejs/http-parser

Tool for measuring webserver performance

https://github.com/httperf/httperf

Improved spell-checker for Hungarian and other languages

https://hunspell.github.io/

Probe for hardware, check operability, and finding drivers

https://bsd-hardware.info/

Portable Hardware Locality software package

http://www.open-mpi.org/projects/hwloc/

Portable Hardware Locality software package

https://www.open-mpi.org/projects/hwloc/

Command line tool to display CPU temp and battery infos

https://BSDforge.com/projects/sysutils/hwstat/

High-performance multiple regex matching library

https://www.hyperscan.io/

Library for high quality hyphenation and justification

https://github.com/hunspell/hyphen

Improved dynamic tiling window manager

https://i3wm.org

Enhanced i3lock with higher capacity

https://github.com/Raymo111/i3lock-color

Iagno

https://wiki.gnome.org/Iagno

Restricted unix shell

http://ibsh.sourceforge.net/

Intelligent Input Bus for Unix-like systems

https://github.com/ibus/ibus

ICE authority file utility for X

Window Manager designed for speed, usability and consistency

https://ice-wm.org/

Displays a wire-frame rotating plyhedron

https://gitlab.freedesktop.org/xorg/app/ico

Utilities of the Tango project

http://tango-project.org/

Basic set of icons for the most common usage

http://tango.freedesktop.org/

Extra set of icons from the Tango project

http://tango-project.org/

Charset conversion library and utilities

Additional charsets for the iconv library (those from the Unicode site)

Additional charset modules for the iconv library (from RFC1345)

Convert/extract images in Microsoft Windows(R) icon/cursor files

https://www.nongnu.org/icoutils/

International Components for Unicode (from IBM)

http://site.icu-project.org/