Asklemmy

Greenshot

Irfanview

Audacity

OBS

Lab Chirp: simple but powerful sound effects generator

Stickies (zhorn software): Networkable sticky notes

Agent Ransack: File content search

Pipewire

Since you're saying "pieces of software" and not specifically apps I will mention Node.js, the programming framework for javascript apps that run outside of a browser. You can develop websites and services or standalone apps that just run locally. There's a whole universe of free packages people have created for it.

Notepad++ is also great for searching text strings in many documents and collating the results in a single window.

Ddrescue

Hard to beat for working with dying drives, although it's a bit tricky to get it to just do used data areas instead of the whole drive.

WinDirStat, Notepad++, Greenshot and Filelocator pro lite (aka agent ransack) are my default programs to install on windows machines.

It's a niche thing, but if you play electric guitar and need a virtual amplifier and effects, you'll like Guitarix very much. Just thinking that is a community project blows me away every time

Krita

EarTrumpet, Borderless Gaming, ClickMonitorDDC, Lenovo Legion Toolkit, FanControl, PEACE + Equalizer APO, Everything, TreeSize

Actual - Accounting/budgeting/etc

Wrote up a python script or three to handle parsing my bank CSV export files into an actually usable form, with automatic categorization, and so now I just do a periodic export and sync, and have all my financial records all in one place with some nice visualization, categorization, and budgeting features from Actual. It saves everything to a local sqlite db, so I can always jump ship to a different system if needed, and also itself provides a CSV export option.

10/10 software, would recommend

OnShape for designing 3d objects. I've been using it for 3 or 4 years, after outgrowing TinkerCad (which is also good and beginner-friendly, but limited). It's an online app, nothing to download or install. The free version is fast and full-featured. The only difference between it and the paid version is that in the free version your designs are all public. So if I were doing 3d design for business I probably would use software that resides on my computer. But as a hobbyist IDGAF.

kate is similar to npp.

Notepad ++ is invaluable for writing code, I’ve used it for a long while now.

Also great is paint dot net which is a super advanced paint application that is borderline as good as photo shop, particularly when you add on all the community-created functionality.

Revo uninstaller is the first thing I put on a new machine before I delete all the bloatware that comes with a fresh install of windows. You would be surprised what is left over when you only use the built in ‘remove a program’ process.

Lastly, browser based but free and excellent, is sketch up, which is an architectural rendering application great for designing restaurants and retail spaces. A little bit of a learning curve but very smooth and functional once you get the hang of it.

Edit - VLC goes without saying right?

VeraCrypt -- creating encrypted partitions/disks with easy manager. I am surprised I did not see anybody to mention it.