Beat Savior is a great site to download custom Beat Saber maps, most of all because you can watch a preview of the level on their website. This makes it really convenient to browse, check, and download the maps.
The biggest gripe I have is that after downloading you have to manually install each map, by creating a directory and unzipping the downloaded file. Yes, there are other ways, but this manual approach makes it possible for me to do this while waiting for, say, some software I’m working on to compile.
So, of course, I automated the process and created BeatZipper.
Once installed in the right place, you just need to drag & drop the ZIP files on the
...\steamapps\common\Beat Saber\Beat Saber_Data\CustomLevels.
The program then proceeds to extract each ZIP file into a directory named after the song and mapper of that ZIP file.
And yes, I know, it should be called “BeatUnzipper”, but that just doesn’t sound as nice.