ZLibrary
IDK about where you live but I'm in Canada and books are stupid expensive. Don't pay for them if you can avoid it.
Theindex.moe
Very good resource if you're into weeb shit.
Newpipe
Ad-free youtube app for mobile, enables background play + popup view; I think the chanel groups feature is especially useful.
Freetube
Ad-free desktop client for youtube. I really hate being advertised to.
Medibang Paint
The desktop version is infinitely better/less annoying but I use both for my digital art.
Calibre
Very good free ebook program, the FanFicFare plugin is great for downloading and saving fanfiction too.
VF Heavy Data
I use this font a lot for my titles/buttons because it came with my digital art program.
Mobile Navigation Menu
I wholesale just ripped the menu base code from here lol
RSS feed tutorial
I'd read through a few other tutorials on how to create an rss feed but this one in particular was the one that I found most helpful.
Atabook
I was very frustrated to find that 123guestbooks would be shutting down before I got to use it, but I think this is a very comparable alternitave.