I will forever recommend VoidTools' Everything ever since someone first introduced it to me some few years ago.

It indexes your entire filesystem and allows you to search for files by name (and by content for text files!) and even allowing RegEx searching for file names, and filters for certain file types and the like.

Power toys.

Made by Microsoft... For Microsoft Windows... To give you Microsoft Windows on crack.

Not sure if it can really be considered hidden, but many people don't seem to know about TreeSize. It's an incredibly useful tool to find out what takes up space on your drives.

Not sure if a hidden gem or not, but WingetUI is pretty handy. You can manage software in winget, scoop, chocolatey, pip, npm and .net with a graphics interface.

Definitely PowerToys, there's some great utilities in there like a Spotlight-esque search/launch bar or a tool to rename multiple files at once.

EarTrumpet is great, too, being basically an enhanced version of the standard audio mixer that lets you change audio devices quickly.

My favourite Windows-only app is probably Foobar2000, though, it's an endlessly customisable music player with hundreds of plug-ins for nearly every conceivable use case. It takes a while to set up but once you do there's nothing better.

Linux

Not technically a program altho it can be, I recommend Privacy.sexy for mass-configuring the best settings for your respective platform (Windows/Linux/MacOS). And there are LOTS of settings to configure for Windows it seems altho thats the case as well for Mac and I can't speak to Linux

SkiFree

TerraCopy and FreeCommander. Fuck Windows Explorer.

TreeSize has saved me a lot of bytes over the years. Performant and visually slick. I would prefer a FOSS utility, though. Apparently, reading other comments here, there isn't an actively maintained one that isn't garbage. Oh well.

Procmon has gotten me out of a couple binds. Task Manager can only do so much for you. I've always been dubious of people who deify Task Manager as some ultimate authority of the OS that kicks ass and takes no prisoners, as I've run into several problems it couldn't solve for me. Procmon feels like the real version of that mythic Task Manager. The main thing it can do which Task Manager (to my knowledge) cannot do that I've needed several times is detect which running processes have a lock on a given file, so I can kill them.

KeePassXC is KeePass2, but not sinfully ugly. It's FOSS and equally functional as the program it aims to supplant, but it's also multiplatform (so I can use it on Linux without Mono!) and it looks like it actually has a design philosophy developed by someone who knows a thing or two about UX design. Also, it lets you auto bulk download favicons for all of your key entries. With KeePass2 I had to do that manually one by one. I was happy to do it then thinking the program was worth it, but now that I know there's a better way I feel like an idiot for putting up with it for as long as I did.

Also, just a short rant: I am so glad Windows finally has a native OpenSSH implementation that ships with the OS. Because that means good fucking riddance to PuTTY and WinSPC. I appreciate them having been there to be our secure and stable options for SSH and FTP/SFTP clients on Windows over the years. But now that I can finally do those things in the terminal with standard cross-platform tools, I no longer have to use their ugly, clumsy GUIs, their stupid .ppk key format, or WinSCP's cryptic command line args ever again, and I couldn't be happier.

DevToys, lots of good tools, handy when you don't want to decode base64 or stuff like that on a website.

https://devtoys.app/

Foobar2000, it is the only windows app that I miss.

Deadbeef is close but it is missing several features, it can't even encode using more than 1 cpu core lol.

MobaXTerm.

Makes dealing with lots of servers, be them Linux or Windows, much easier.

Honourable mention to Right PDF reader for helping me with previous study too. It's had a name change but it includes enough features in its free version that makes it very good for reading and marking up longwinded academic studies.

KeepassXC with browser plugins

Notepad++

ShareX for super easy and configurable screen shotting and recording

Espanso text expander

Everything for search

Wox for quick launching

Chocolatey, a command line driven package installer for Windows that works like apt-get for Linux. Replaces thousands of bloated installers with simple commands. My first step with an updated Windows install is to install Chocolatey, open command prompt, and do something like choco install firefox notepadplusplus gimp zoom windirstat winrar to install them all silently.

AtlasOS, easily. Makes my slightly-older PC run like new.

For video, virtualdub2 and avisynth. Avisynth let's you handle video as if it were a variable in a program. This lets you do things impossible with a regular video editor.

Rufus. It's an app that let's you create a bootable USB of a Linux distro so you can leave Windows behind.

I use IPFilter Updater for Bit Torrent programs.

It updates a block list that blocks out bad actors and trackers, so there's a bigger chance you can sail the seas in peace.

The speed at which new users can download Rufus and have linux installed over that shit is truly amazing.

Sharex

My favorite hidden gem has to be ear trumpet (https://eartrumpet.app/). It gives you quick access to changing app volume without going through multiple clicks.

FancyWM

If I absolutely have to use windows it works pretty well in letting me keep my workflow from Linux along with some hotkeys for cycling virtual desktops

Pretty sure WinSCP is the best SCP/FTP client on any platform.

I recently found out about PeaZip, it's a Foss compression tool that can compress and uncompress a wide variety of compression formats. For some formats, like 7z, it also has some pretty advanced options to help maximize compression ratios, if you know what you are doing of course.

Winutil. Makes windows usable.

Startisback++, not tried on Win11.

Firefox/Brave, VLC, 7zip, to replace the garbage apps

Alt+F4 automatically closes any programs wasting your time.

the Ditto clipboard manager

It lets me keep track of all my clipboard history without having to use microsoft's

only thing is I have to remember to go back and delete a password after I copy it, but luckily bitwarden can autofill most of the time

Baregrep is really great for parsing tons of logs

Notepad++ for syntax highlighting, don't even need to read the words, just look at the patterns of colours to understand the logs

WinMerge for comparing files between folders, I use it often to compare code between deployment versions

https://github.com/MustardChef/WSABuilds/releases/tag/Windows_11_2309.40000.2.0