Filters posts with delay, i.e., first the page loads and then the blocked posts are removed. You need to enter subreddit names manually. Could be better, however it is the only one that works.

they must have fixed it cause it works now.
it's case sensitive so you have to type the subreddit name exactly, you don't need the r/ part, and also takes a second to load.

you will see a subreddit you thought you blocked but give it a second and it goes away.
it's good but it needs a button next to the subreddit name to block it. i would give it 5 stars if that feature was there.

Just straight up does not work. Stopped working a few weeks ago and the lack of updates had me just delete it

There's not a lot of details on this addon and how it works, so it's hard to say if its working as intended, but for me it does not work well. I use the "new" design, and the addon doesn't do much there, so not sure if it was meant for the "old" design. I very occasionally see a post for a blocked sub disappear because of the addon, but very rarely, and most of the time it does nothing (meaning I see tons of posts from blocked subs while viewing r/all). There are a few other minor nitpicks, like it doesn't prevent you from adding duplicates to the block list. But overall, it's just not effective.