Almost completely open-source and free.
Online Service Recommendations
Recommended For Developers
Oracle VM VirtualBox: Cross-platform virtualization software.
try.dot.net: Compile and run C# from your browser.
asciinema: Record and share your terminal sessions, the right way.
Pro Git: Free e-book. Everything you need to learn Git.
Getbootstrap.com: The worlds most popular HTML, CSS and JS library.
FontAwesome.io: Iconic font and CSS toolkit.
JQueryForm.com: Professional web form builder, mobile-friendly.
WordPress.org: Open-source content management system.
Google.ai: Learn with Google AI.
GIMP: Open-source image editor.
Inkscape.org: Professional vector graphics editor.
OpenShot.org: Award winning open-source video editor.
Blender.org: Open-source 3D creation suite.
UnrealEngine.com: Professional game development tools.
OpenToonz: Open-source animation production software.
Audacity: Open-source cross-platform audio software.
Recommended for Security and Anonymity
Privacy and Anonymity Tool Kit: Blog post by Hayward.
TorProject.org: Improve your privacy and security online.
Startpage.com: The worlds most private search engine.
ProtonMail.com: Secure email based in Switzerland.
ProtonVPN.com: Secure and Free to Premium VPN Service.
Qubes-OS.org: A security-oriented operating system (OS).
Keybase.io: Public-key cryptography for everyone.
Mega.nz: Secure cloud storage and messaging,
Zoho Vault: Password manager, free for personal use.
Recommended Apps (General)
PendriveLinux.com (YUMI): Multiboot USB creator.
FileZilla: Free FTP client with plenty of features.
GIMP: GNU Image Manipulation (opens source image editor).
LibreOffice: Free office suite (open source alternative to MS Office).
Mozilla Thunderbird: Customisable feature rich email client.
VLC Media Player: Open source cross-platform multimedia player.
TeamViewer: Remote access and support (free for personal use).