Office
LibreOffice
Free and Open Source alternative to the Microsoft Office Suite. Has alternatives to Word, Powerpoint and Excel, for instance LibreOffice can open and save to Microsoft file formats, OpenDocument, and many others.
https://www.libreoffice.org/
Scribus
Printer quality publishing application. Create signs, brochures, and newsletters.
http://www.scribus.net/
Browsers
Firefox
Open Source alternative to Chrome, Edge, and Safari. Developed by Mozilla this browser is slightly more secure out of the box and can be made even more secure with a few tweaks. Has a number of great addons as well.
https://www.mozilla.org/firefox
Brave
A Chromium based browser that is built with a focus on user privacy and blocks ads and web based trackers by default.
Thunderbird
Thunderbird is a mail and news reader with much of the same functionality that Outlook has.
https://www.thunderbird.net
Audio
Audacity
The premier audio editing tool. This program allows you to record, modify and mix audio for a variety of projects. It is used to build podcasts and create full-length CDs.
http://audacity.sourceforge.net/
CDex
Rip CD Audio into WAV files. You can also compress the files using add-in programs to convert the files to mp3.
https://cdex.mu/
Images
GIMP
An open-source image editor, an alternative to Adobe Photoshop.
http://www.gimp.org/
Video
MythTV
Create a PVR so that you can record live TV and store your DVD collection for easy playback.
http://www.mythtv.org/
MPC-BE
Based on Media Player Classic and Media Player Classic - Home Cinema. MPC-BE is a lightweight, open source, no-frills video player that just works.
https://sourceforge.net/projects/mpcbe/
Plex
Plex is a software suite designed for video storage and streaming containing both a client and server. Media is hosted on a local server and can be watched on the web or via an app which is available on a number of streaming devices.
Antivirus
Windows Defender
The built in Antivirus for Microsoft Windows, comes already installed and works out of the box.
https://www.microsoft.com/en-us/windows/comprehensive-security
MalwareBytes
When Windows Defender doesn't offer enough protection MalwareBytes is the perfect complement.
MISC
CD Burner XP Pro
Not open source, but still a great CD burner. It will burn several types of CDs and DVDs. It will also burn a CD from an ISO.
http://www.cdburnerxp.se/
VirtualBox
Software designed for the creation and management of virtual machines. Originally developed by Sun Microsystems both were acquired by Oracle in 2010 but virtualbox has remained open source as of 2018.
An Extended List of Open Source Free Tools for Windows
Audio Editing Tools
System Utilities
1. BleachBit
• Website: bleachbit.org
• Description: A system cleaner that frees up disk space by deleting unnecessary files and protecting privacy.
2. Clonezilla
• Website: clonezilla.org
• Description: A partition and disk imaging/cloning program to back up and restore entire systems.
3. GParted
• Website: gparted.org
• Description: A partition editor that allows you to resize, copy, and move partitions without data loss.
4. PowerToys
• Website: github.com/microsoft/PowerToys
• Description: A set of utilities developed by Microsoft to enhance productivity, including tools like FancyZones for window management.
5. Sysinternals Suite
• Website: docs.microsoft.com/en-us/sysinternals/
• Description: A collection of advanced system utilities and technical information to troubleshoot and manage Windows systems.
Security & Privacy
6. KeePass
• Website: keepass.info
• Description: A free, open-source password manager that helps you store and manage passwords securely.
7. VeraCrypt
• Website: veracrypt.fr
• Description: A disk encryption software that allows you to encrypt your data and partitions for enhanced security.
8. Bitwarden
• Website: bitwarden.com
• Description: An open-source password manager that allows you to store and manage your passwords across devices securely.
9. Wireshark
• Website: wireshark.org
• Description: A network protocol analyzer that lets you capture and interactively browse the traffic running on a computer network.
10. OpenVPN
• Website: openvpn.net
• Description: An open-source VPN software that allows you to create secure point-to-point or site-to-site connections.
File Management
11. 7-Zip
• Website: 7-zip.org
• Description: A file archiver with a high compression ratio, supporting numerous file formats.
12. PeaZip
• Website: peazip.org
• Description: A file archiver and compressor that supports more than 150 file formats.
13. FreeFileSync
• Website: freefilesync.org
• Description: A folder comparison and synchronization tool that helps you back up and synchronize your data.
14. WinMerge
• Website: winmerge.org
• Description: A tool for visual difference display and merging, useful for comparing files and folders.
15. qBittorrent
• Website: qbittorrent.org
• Description: A free and reliable P2P BitTorrent client that aims to provide a free alternative to uTorrent.
Productivity
16. LibreOffice
• Website: libreoffice.org
• Description: A powerful open-source office suite that includes word processing, spreadsheets, presentations, and more.
17. Notepad++
• Website: notepad-plus-plus.org
• Description: A powerful text editor that supports several programming languages, ideal for coding and editing text files.
18. Scribus
• Website: scribus.net
• Description: A desktop publishing software that allows you to create professional-quality documents with high-quality typography.
19. Zotero
• Website: zotero.org
• Description: A tool that helps you collect, organize, cite, and share research sources.
20. Todoist (Open-source version)
• Website: github.com/Krasjet/todoist
• Description: A self-hosted, open-source version of the popular Todoist task manager.
Multimedia
21. GIMP
• Website: gimp.org
• Description: A powerful image editor and graphics creation tool, often considered an alternative to Adobe Photoshop.
22. Audacity
• Website: audacityteam.org
• Description: A free, open-source, cross-platform audio software for multi-track recording and editing.
23. Shotcut
• Website: shotcut.org
• Description: A free, open-source, cross-platform video editor that supports a wide range of formats and features.
24. HandBrake
• Website: handbrake.fr
• Description: A video transcoder that allows you to convert video files into different formats.
25. VLC Media Player
• Website: videolan.org
• Description: A free and open-source media player that plays most multimedia files, as well as DVDs, audio CDs, and various streaming protocols.
Development Tools
26. Visual Studio Code
• Website: code.visualstudio.com
• Description: A lightweight but powerful source code editor that supports a wide range of programming languages and frameworks.
27. Eclipse
• Website: eclipse.org
• Description: An integrated development environment (IDE) that supports various programming languages, including Java and C/C++.
28. Git
• Website: git-scm.com
• Description: A distributed version control system that helps developers track changes in source code during software development.
29. XAMPP
• Website: apachefriends.org
• Description: A free and open-source cross-platform web server solution stack package developed by Apache Friends, consisting mainly of the Apache HTTP Server, MariaDB database, and interpreters for scripts written in the PHP and Perl programming languages.
30. Docker
• Website: docker.com
• Description: An open platform for developing, shipping, and running applications in containers.
Backup & Recovery
31. Duplicati
• Website: duplicati.com
• Description: A free backup software to store encrypted backups online for Windows, macOS, and Linux.
32. Restic
• Website: restic.net
• Description: A fast, secure, and efficient backup program that supports various storage backends.
33. Rclone
• Website: rclone.org
• Description: A command-line program to manage files on cloud storage, offering features like encryption and sync.
34. Rescuezilla
• Website: rescuezilla.com
• Description: A free and open-source disk imaging software that allows you to back up and restore your entire system.
35. Areca Backup
• Website: areca-backup.org
• Description: A file backup software that supports incremental backups, encryption, and compression.