1- office for my work
2- antivirus - for safety
3- idm - download
4-winrar- a lot rip file now
5- foxit phantom pdf- help me to do anything with pdf ( also easy to get key )
I think these are good webmaster tools, not in general:
Sublime Text - an excellent text editor with highlighting for different languages. It's technically not free, but the trial allows unlimited, full use - it just bugs you to consider buying it every 20 saves.
PuTTY - If your hosting provider is a VPS or dedicated server provider, you can access your Linux distro's SSH using this tool. It's lightweight and free too, plus it can fit on a flash drive. Easier than getting SSH from Cygwin.
FileZilla - Excellent FTP tool. It supports SFTP also and is very fast, however, you have to download it in a certain way if you don't want the bundled software (or adware as some call it).
If you use PuTTY and manage a lot of machines, I recommend RoyalTS. The ability to manage 30+ sessions in one application saves your sanity. It uses PuTTY, just hooks it into one application. Also supports RDP/VNC etc in the same app. When I'm not on Windows (which has been more and more of recent), iTerm3 is a good replacement for Terminal on Mac. I haven't found a good terminal replacement on Ubuntu yet.
Some of the Common softtwares are given below which is necessary to use in any OS are: -
MS Office
VLC Media Player
WinRar
Google Chrome/Mozilla Firefox
Adobe Reader