Lemmy itself allows you to block communities, instances, and users. But it does not support filtering by keyword, e.g. filtering out any post with the word "platypus" in the title regardless of where it was posted or by whom. With help from the comments below, here are some third party Lemmy clients that have their own implementation of keyword filtering:

Boost
Connect
Eternity
Interstellar
Raccoon
Summit
Sync
Tesseract
Thunder
Voyager

Do NOT support keyword filtering:

Alexandrite
Jerboa
Lemmy UI
mlmym
Next
Photon
Quiblr

Comment anything I have missed or mistakes I made

https://feddit.org/post/3857608

[–] fxomt@lemmy.dbzer0.com 8 points 1 week ago (1 children)

Yeah, unfortunately unlike piefed's (which persists across all sessions) you have to manually set the filters for each app you use tho. Thanks for the list of apps tho :)

[–] mesamunefire@piefed.social 3 points 1 week ago

Piefed can also have an expiration date just in case you want xxx days of no politics etc...

[–] nutomic@lemmy.ml 8 points 1 week ago (2 children)

Keyword filters are work in progress: https://github.com/LemmyNet/lemmy/pull/5263

[–] fxomt@lemmy.dbzer0.com 4 points 1 week ago

Damn, nice. I see you're all working hard on it, GL and thanks!

[–] Blaze@lemmy.dbzer0.com 2 points 1 week ago

Niiice

[–] mesamunefire@piefed.social 5 points 1 week ago

I believe there might be filters on some cell apps specifically for Lemmy? Maybe someone else can chime in.