Some mods and utils that I couldn't (or it was insanely hard to) find on the web, or that i'm just archiving.
Mod Installers
Legacy (1.4): ModInstaller.exe (my cloud) or ModInstaller.exe (directly from radiance's website) or ricardosouzag/ModInstaller (GitHub)
Current (1.5): Lumafly(Recommended) or Scarab
Both Legacy and Current search for mods in "Hollow Knight"/hollow_knight_Data/Managed/Mods/, except with a small difference: Legacy searches for dll files directly from the Mods folder, while the Current one searches in every folder inside the Mods folder, both without recursing.
About 1.4 mods like Art Mods not installing (giving error)
If you're trying to install 1.4 mods and it's saying the "Central Repository" is corrupt, that probably means the URL for downloading the mod is dead. A lot of 1.4 mods were hosted in radiance's site, but they changed domains (from radiance.host to radiance.synthagen.net), so the modinstaller links broke. One way to circumvent this is by going into the modlinks.xml (The database where all the mod links are stored), looking for the mod's link and change it to radiance.synthagen.net. Then it will download and you can put on the mods folder manually.
Modded Radiances
Any Radiance
Download 1.4: Any_Radiance.dll
Download 1.5: Any1578.dll (needs Satchel to work properly)
It's between Ultimatum and Atomic. For what was supposed to be a joke, it's not so bad.
Dumb Radiance
Download: EAradiance.zip
I couldn't get this one to work
Atomic Radiance
Download: artmods.zip
Modlinks says it requires Modding API and ModCommon.
Has a ton of RNG bullshit, you were warned.
Ultimatum Radiance
Available in ModInstaller 1.4, just install Ultimatum Radiance there.
In case it doesn't install, there's "my mirror", where you can download and install manually: [API] Ultimatum Radiance (by Alek Fleischer).zip
Modlinks says it requires Modding API and ModCommon.
A port for 1.5 is also available: Ultimatum Radiance 1.5
This radiance is very good; very fair and fun to play.
Nightmare Ultimatum Radiance
Download: Nightmare_Ultimatum_Radiance.dll
I don't remember being able to make this work either.
Custom Levels
There's a Googol Drive folder full of levels: Hollow Knight Custom Levels