Random Collection of Open Source and Freeware Utilities for Windwos-10 Users

1. Productivity Tools:
• LibreOffice Suite: Includes a Spreadsheet (Calc), Word Processor (Writer) and a Presenter (Impress). Most popular alternative to Microsoft Office.
• Thunderbird: Email Client, simple and efficient. Most popular alternative to Microsoft Outlook.
• SumatraPDF: Simple PDF Reader for those who want to avoid the cost and bloat of Adobe Reader.
• WordWeb: Free and Popular Dictionary Software.
• WinCDEmu: Very useful CD/DVD emulator that creates a virtual drive 
2. Networking and Internet:
• Firefox: Privacy friendly alternative to Edge/IE, configurable and open source browser.
• Chrome: Another alternative to Edge/IE from Google's stable. Integrates well wither other Google products, a speedy and secure browser.
• WinSCP: The Windows way of "SSHing" to a Linux Server.
• Putty: Another great tool to SSH into a Linux box.
• CuteFTP: FTP client for transferring files using the FTP/SFTP/FTPS protocols.
• FileZilla: Another popular FTP client in the Windows world, but be careful as their developers were involved in adware bundling on Sourceforge recently.
• WGET: Command line tool to quickly download files through HTTP/HTTPS. Supports resuming downloads paused by pressing "Ctrl+C".
• TCPView: Useful tool from sysinternals to quickly view all TCP connections on your PC.
3.  Security and Anti Viruses:
• ClamWin: Stand-alone anti-virus scanner for the plebeians who can't afford McAfee or Norton, has a portable version too.
• KeePass2: Excellent tool to store your encrypted passwords in one place, open source and written in C#.
• Rufus: Excellent tool to create a bootable Pen-Drive or DVD from Windows/Linux ISOs.
• CCleaner: Registry Cleaner from the stable of Piriform.
4. Software Development:
• Notepad++: The Programmer's editor of choice on the Windows platform!
• Visual Studio Code: A lighter version of Visual Studio IDE, good competition to Notepad++. Free, open source and comes from the Microsoft stable.
• Visual Studio Community Editions: Visual Studio IDE for the plebeians and freelancers! Feature-full and has almost all the features of Pro edition, only limitation is that you can't use this if you are a commercial enterprise entity (5+ employees or more than one million revenue). But perhaps a great boon for individual developers and freelancers.
• Visual Studio Express Editions (Scroll down to "Still want VS Express?"): If you cannot use the Community Edition for licensing terms or other reasons, you can always get the older Express editions that don't have any such limitations.
• Eclipse: The popular open source IDE for Java developers, but also supports PHP, Python, C/C++ and some other languages through plugins.
• Netbeans: Another IDE for Java development, also supports PHP and C/C++.
• Git: Git is not just a version control system, but also installs msysgit which is almost stripped-down version of the Bash shell. It comes with basic commands and GNU utilities, so you don't even have to bother with Linux subsystem on Windows-10.
• ConEmu: A more powerful alternative to CMD.exe, you'll find especially useful if you come from Linux environment and are used to tools like bash.
• Python: A must if you are a Python developer who works on the Windows platform.
• XAMPP: A must if you are a PHP/MySQL developer who works on the Windows platform.
5. Graphics and Image Editing:
• GIMP: The ultimate open source raster graphics editing tool.
• Inkscape: The ultimate open source vector graphics editing tool.
• Paint.NET: A simple and lighter version of GIMP, easier to comprehend and use. Requires the super-latest version of .NET 4.x framework installed though.
6. Multimedia:
• VLC: Perhaps the most popular Video/Audio player on Windows.
• Gnome-Subtitles: Tool to create and edit subtitles.

This collection is by no means comprehensive! Feel free to comment on this post and suggest more recommendations.