GNU/Linux software

KDE

Qt, beautiful and customizable desktop environnement
https://kde.org

Communication

Evolution

GTK, GNOME Mail client

Thunderbird

Mail client
https://www.thunderbird.net

Nheko

Qt, Matrix client
https://nheko-reborn.github.io

SchildiChat Desktop

Electron, Matrix client, fork of Element
https://schildi.chat/desktop

Downloaders

qBittorrent

Qt, torrent client
https://www.qbittorrent.org

Nicotine+

GTK, Soulseek alternative client, P2P proprietary network aimed at sharing files, especially music
Warning: as far as I know, network traffic is not encrypted
https://nicotine-plus.org

FileZilla

GTK, FTP/FTPS/SFTP client
https://filezilla-project.org

youtube-dl-gui

GTK, GUI for youtube-dl
https://mrs0m30n3.github.io/youtube-dl-gui

Hypertext browsers

Kristall

Qt, customizable and privacy friendly hypertext client supporting HTTP/Gemini and HTML/Markdown/Gemtext (and more)
https://github.com/MasterQ32/kristall

LibreWolf

Privacy enhanced Firefox fork
https://librewolf.net

Tor Browser

Privacy enhanced Firefox fork, using the Tor network
https://www.torproject.org

Ungoogled Chromium

Chromium fork, without any communication or link to Google servers
https://ungoogled-software.github.io

Graphics

GIMP

GTK, image manipulation program
https://www.gimp.org

Inkscape

SVG image editor
https://inkscape.org

LibreSprite

Animated pixel art creator
https://libresprite.github.io

Audio & video

Clementine

Qt, music player
https://www.clementine-player.org

VLC

Video/audio player
https://www.videolan.org/vlc

Audacity

Audio recorder and editor

Text

Atom

Electron, code editor
https://atom.io

ghostwriter

Qt, markdown editor
https://wereturtle.github.io/ghostwriter

Meld

GTK, compare similar files

Miscellaneous

Bitwarden

Electron, password manager
https://bitwarden.com

Lector

Qt, ebooks reader (PDF, EPUB)

Zeal

Qt and webview, Offline programmation language documentation reader
https://zealdocs.org

Kiwix

Webview, offline ZIM files reader, works with Wikipedia, Wiktionnary, Stack Exchange
https://www.kiwix.org

MultiMC

Qt, Minecraft launcher

OnionShare

Publish site, share and receive files over Onion
https://onionshare.org

QtQR

Qt, QR code generator

AppImage launcher

Integrate AppImages to system

FSearch

GTK, indexes all your filesystem in order to search in it

Octopi

Qt, Arch Linux package manager
https://bitwarden.com

DB Browser for SQLite

Qt, edit SQLite databases

CLI

Fun with CLI