What free offline, local desktop software do you like and would recommend?

Equalizer APO if on Windows
Audio equalizer that can have separate settings for individual devices.

Notepad++
Like the classic Windows Notepad, but on steroids.
- I prefer NotepadNext, it's a cross-platform reimplementation.
- Thanks for the reminder to put the dev on my annual donate list.
  One of the best pieces of software I've ever used. Easy to use for a newb , with so much capability.
- My favorite part about Notepad++ is pressing ALT and then selecting a line and then you can edit multiple lines of text at the same time.
  Well, that and the fact that it's an amazing piece of software that is continuously improved and free and just generally all around the best at what it is.

KeePass2 as a pasword manager. Less convenient than online, but so much safer, there's also Kee, a browser extensions that connects to the database locally and autofill passwords in sites
- Keepassxc
- Less convenient than online, but so much safer
  What are the advantages over saving the passwords directly in the browser, or using a paid service?
  
  I would say your attack surface area is reduced. Last pass and bitwarden are huge targets for state sponsored cyber attacks.
  Also no lock in. I use the same password db with multiple browsers simultaneously.
  There is no paid tier. All features available. Storing SSH keys for example.
  I use my db to store all sorts of information, not just passwords. For example, I need to manage heaps of physical keys. I stamp them with a serial like k23 and store details about the key in my db.
  Keepassxc also does TOTP. Some aren't into that which is fine but I don't see any benefit in using a separate app.
  
  If stored in a browser, your passwords become very obvious targets for stealer malware (the stuff that does account takeovers). Using keepass or other similar software won't make it impossible for malware to get them, but the likelihood malware will target it is significantly lower.
  Paid services put your passwords in the hands of the service. In the case of a data breach (see LastPass), all your passwords will get out.
  Note: Password manager services should encrypt your data such that a data breach does not instantly pwn every single account of every single customer. However it is not possible for you as the customer to know until they get breached.
  Note 2: When storing your passwords in the browser, they may also end up stored in Google or Mozilla's (and so on) servers, resulting in the worst of both worlds for security: Passwords are in a well-known location on your PC and a well-known location on the internet.

Definitely Blender for everything with 3D graphics.
Blender 4.4 was released recently: https://www.blender.org/
- Blender has a decent video editor as well. You can even automate stuff with Python.

Godot. Open source game engine that is similar to Unity.
- I just started learning this a week ago and it’s surprisingly quick to pick up if you’re coming from Blender. I struggled a ton with Unity and Unreal, but Godot’s approach to things work well for my brain.

I really like using Shotcut for video editing. It just makes sense to me. It's quick and easy, and I know there's other software like I'm sure somebody's gonna jump out and say DaVinci Resolve or something, but it works for my purposes.

X-Inkscape - vector drawing
- and GIMP vor pixel drawing
  
  I think Krita is more suited for that

A couple I like to use occasionally are LibreOffice Draw and Freeplane. Draw is for diagramming and technical drawing, and Freeplane is for mind-mapping (which is sort of another way to say diagramming).
Despite having used LibreOffice's other software for awhile, I had completely overlooked Draw, which is why I ended up finding Freeplane. Both are great open source programs for sorting out information, diagramming and outlining ideas with a more free form visual arrangement.
- I'm trying to get mum onto libre office. She's stubborn and is paying some unreasonable amount for a word subscription.
  
  Tell your mother she can "pay" less than half of that amount to LibreOffice Foundation and they will still deliver a full office suite and perhaps even send her a very warm thank you message.

Big fan of Geany lately as my text editor and IDE. Really great, fast, lightweight, piece of software.

vim. It has 2 modes: spoil the text and beep. Cool, huh?
- My favourite is when you forget to press I or a and end up in some mode I never knew existed