Buy nothing groups.

https://freecycle.org/

I just drop them off at the thrift store. If it's something that I think would really benefit someone less fortunate who couldn't afford it at the thrift store, then I put it on Craigslist or offerup. Offerup is annoying though, so I only use it for stuff that would appeal to a younger audience, since youngsters seem to want an app for everything, even things that work just fine as a website.

There are some local classified websites where you can post stuff for free and there are also multiple nearby thrift stores for second hand stuff that will sell things very cheaply for you if you waive your own part of the price.

I adore free little libraries and free little pantries (for food), but online I have also seen free tool sheds, clothing "closets," and craft boxes. I love the idea of these so much. Imagine an apartment building having a tool shed or a craft box, so that when you are done with your hobby, you can pass the tools onto someone else. Some people mark the address and purpose onto the tools so they can't be resold.

Also, you never know who in your neighborhood needs help, so this is a quiet way of helping people.

There's a lot of donations boxes scattered all around my town from various projects for helping the homeless and poor. They've become common the last half decade. Don't remember seeing much before. Salvation army/churches are also a common donation choice in my area. Can also give or sell them to a thrift shop or flea market I guess. I prefer the donation boxes run by what at least seem to be non-church charities, personally. Been using 'em quite a bit cleaning out my house.

Craigslist has a /zip channel in every region that's usually pretty active with furniture takeaways and curb alerts.

My neighborhood Facebook page. Just set stuff out on the curb and post a picture of it and it starts disappearing