3 of 5 links contain non-worksafe boards.
4chan has... well... 4chan.
7chan has a Rule 34 board.
iichan has an uncenscored & niche board.
4chan is fairly work safe as long as you don't wander onto b, d, e, gif, h, r, s, t, u, and y.
a, an, cgl, ck, co, g, k, m, mu, o, p, po, sp, tv, v, w, wg Are for the most put safe except for btard raids.
can't be bother doing the same for 7chan and iichan
But if in doubt read
If you want to be that critical about NSFW, Don't go on the internet. Its just riddled with all kinds of "STUFF"
. Its not safe for anyone.
BTW I found this on 4chan.
So its not all bad