Android
OSMAnd (instead of Google Maps)
Thorium (PeerTube instead of Youtube)
Red Moon Android (for night light on Android)
Antenna Pod (podcast on Android instead of Itunes)
KeePassDroid (for keeping/generating complex password)
Tusky (for Mastodon on Android)
Signal (instead of Whatsapp)
On your PC
Ubuntu/Linux Mint/Debian etc... (instead of IOS or Windows)
gtkpod (podcast transfer to ipod)
KeePass XC (for keeping/generating complex password)
Mattermost (instead of Slack)
Sengi (for Mastodon on Ubuntu)
System monitor: Conky (for Linux)
LibreOffice (instead or Microsoft pack office)
Gimp (instead of Photoshop)
On the internet
Framasoft : popular educational organization (a lot of free and open-source softwares)
Pixelfed : free open source alternative to Instagram (a lot of free and open-source softwares)
chatons.org : collective of independant, transparent, open, neutral and ethical hosters providing FLOSS-based online services
Qwant/Ecosia/Duckduckgo (instead of Google)
Open Street Map (instead of Google Maps)
PeerTube (instead of Youtube)
Mozilla firefox (instead of Google Chrome) + add on:
*HTTPS everywhere
*I don't care about coockies
*Invidious Redirect (privacy on Youtube)
*Peertubeify (find Youtube video on PeerTube)
*uBlock Origin (blocks adds)
*uBlock (blocks adds)
*NoScript (block JS)
*QuickJava (de/reactivate Java, Javascript, Flash ou Silverlight)
*Clean Links ou RedirectCleaner (correct weird URLs)
*Remove Google Tracking
*Lightbeam (displays third party tracking cookies)
*Disconnect (see all of the invisible tracking and unsecured connections)
*Privacy Badger (blocks spying ads and invisible trackers)
*CookiesManager+ (manage coockies)
*Self-Destructing Cookies (delete cookies)
*Close 'n' forget (delete cookies and history)
*BetterPrivacy (control cookies)
*Random Agent Spoofer (send wrong information)
*FoxyProxy/SwitchProxy
Matomo (instead of Google Analytics)
Tutanota/protonmail (instead of Gmail/Hotmail etc...)
thepiratebay and Transmission to download stuff
Open Science
Zotero + Zotero connector for Mozilla (bibliography)
semanticscholar.org (Scientific articles)
sci-hub.se (check the internet for the latest working version) sci-bay.org (Scientific articles) gen.lib.rus.ec (books)Python/R (instead of Matlab)