Hydrus is a desktop booru developed by Hydrus Dev. It has been in development for a few years, but I don’t really care how many.
Hydrus’ main purpose is image and video management through tagging. You add tags to files and then use the tags to search for files. It’s fairly simple. Compare to FenrirFS, another program based around tagging.
The whole thing has a bunch of other features, most of which I’ve never actually used.
One particularly great thing about Hydrus is the downloading. There are a number of different ways to download things but the “best” way is through the gallery downloader. Here you essentially pick an existing website, then you input a search term for it and Hydrus starts downloading. Alongside the images, Hydrus can also import the tags… so you don’t have to manually add them.
One thing I wish Hydrus added support for would be Danbooru-style notes, so I can start downloading manga from there as well.
When downloading you should use one of these. I tried both and so I’ll share which I think is better.
I should be more specific though. You should create a list of artists you like and then place that list into a whitelist that you’ll use when downloading. Why a whitelist and not a blacklist? Because keeping track of what you like is easier than keeping track of what you don’t like. Most art is kinda bad so it doesn’t make much sense to keep track of the bad stuff, your blacklist would just get larger and larger (which is exactly what happened to me!)