Hanzi Converter -- converts between GB and BIG-5 codes

Hierarchical Data Format library (from NCSA)

https://www.hdfgroup.org/

Hierarchical Data Format library (from NCSA) 1.10.x

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

HFSExplorer read Mac-formatted harddisks and disk images

https://www.catacombae.org/hfsexplorer/

FUSE driver for HFS+ filesystems

https://github.com/0x09/hfsfuse

Utilities for accessing Apple's HFS volumes

https://www.mars.org/home/rob/proj/hfs/

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

Nintendo multi-system emulator

http://byuu.org/higan/

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

Hyper NIKKI System, a CGI system for Electric Diary Interchange

http://www.h14m.org/

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/

HMM-based speech synthesis system (HTS) engine and API

https://hts-engine.sourceforge.net/

HTTP request/response parser written in C

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

FUSE filesystem to mount HTTP directory listings, with a permanent cache

https://github.com/fangfufu/httpdirfs/

Tool for measuring webserver performance

https://github.com/httperf/httperf

Fuse-based http filesystem

https://httpfs.sourceforge.net/

Improved spell-checker for Hungarian and other languages

https://hunspell.github.io/

Probe for hardware, check operability, and finding drivers

https://bsd-hardware.info/

Database of IDs used in PCI, PNP and USB devices

https://github.com/vcrhonek/hwdata

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/

Program to generate a cross-referenced HTML mail archive

http://www.hypermail-project.org

High-performance multiple regex matching library

https://www.hyperscan.io/

Library for high quality hyphenation and justification

https://github.com/hunspell/hyphen

Wayland protocol extensions for Hyprland

https://github.com/hyprwm/hyprland-protocols

Official implementation library for the hypr config language

https://wiki.hypr.land/Hypr-Ecosystem/hyprlang/

Hyprland utilities library used across the ecosystem

https://github.com/hyprwm/hyprutils

Hyprland implementation of wayland-scanner

https://github.com/hyprwm/hyprwayland-scanner

Fast and consistent wire protocol for IPC

https://github.com/hyprwm/hyprwire

Heterogeneous set of I2C tools

https://i2c.wiki.kernel.org/index.php/I2C_Tools