Youtube videos downloader

https://github.com/kkdai/youtube

Command-line YAML and XML processor, jq wrapper for YAML/XML documents

https://kislyuk.github.io/yq/

Unpack data in MS Outlook TNEF format

https://github.com/Yeraze/ytnef

Seamless ssh-agent for YubiKeys

https://filippo.io/yubikey-agent

Encrypted peer-to-peer IPv6 UDP messaging terminal

https://github.com/yamafaktory/yume

Fastest JSON library in C

https://github.com/ibireme/yyjson

Maintain and replicate ZFS snapshots

https://github.com/Jehops/zap

Dynamically typed N-D expression system based on xtensor

https://github.com/xtensor-stack/zarray

Compressed file format that splits the file into independent chunks

https://github.com/zchunk/zchunk

Fast CLI DNS lookup tool

https://github.com/zmap/zdns

Event logging framework - engine

http://zeitgeist-project.com

Simpler web photo gallery

https://www.zenphoto.org/ https://github.com/zenphoto/zenphoto

Network virtualization everywhere

https://github.com/zerotier/ZeroTierOne/

Zetaback ZFS backup and recovery management system

https://github.com/omniti-labs/zetaback/

ZFS Snapshot Replication Script

http://blogs.sun.com/constantin/entry/useful_zfs_snapshot_replicator_script

View ZFS snapshot differences via a web browser

https://github.com/j-keck/zfs-snap-diff

Tool to sieve ZFS snapshots as per given spec a la 'pdumpfs-clean'

http://github.com/knu/zfs-snapshot-clean

Display human-readable ZFS statistics

http://www.vx.sk/zfs-stats/

Simple sh script to make zfs rolling snaphosts with cron

https://github.com/graudeejs/zfSnap/

Portable performant script to make rolling ZFS snapshots easy

https://github.com/zfsnap/zfsnap

Simple and opinionated tool to build your own magazine

https://zineland.github.io

Create/update ZIP files compatible with PKZIP

http://www.info-zip.org/Zip.html

Library for the Signal Private Group System

https://github.com/signalapp/zkgroup

Fork of the zlib data compression library

https://github.com/zlib-ng/zlib-ng

C library for polynomial arithmetic

https://web.maths.unsw.edu.au/~davidharvey/code/zn_poly/

CLI tool for querying DNS records with readable and colored output

https://github.com/znscli/zns

Zopfli Compression Algorithm

https://github.com/google/zopfli

Fast cd alternative that learns your habits

https://github.com/ajeetdsouza/zoxide

ZFS pool I/O latency statistics

https://github.com/chadmiller/zpool-iostat-viz

Tool for managing Zshell plugins inspired by Vundle

https://github.com/zsh-users/antigen

Fish-like autosuggestions for Zsh

https://github.com/zsh-users/zsh-autosuggestions

Additional completion definitions for Zsh

https://github.com/zsh-users/zsh-completions

Optimized and extended zsh-syntax-highlighting

https://github.com/zdharma-continuum/fast-syntax-highlighting

Curses-based tools for Zshell, e.g. multi-word history searcher

https://github.com/psprint/zsh-navigation-tools

Fish shell syntax highlighting for Zsh

https://github.com/zsh-users/zsh-syntax-highlighting

C++ header-only ZLib wrapper

https://github.com/mateidavid/zstr

Display ZFS dataset I/O in real time

https://github.com/asomers/ztop

Easily and reliably transfer ZFS filesystems

https://github.com/allanjude/zxfer

Framework for proximity-based peer-to-peer applications

https://github.com/zeromq/zyre

Library to provide transparent read access to zipped files

http://zziplib.sourceforge.net/