Open source, self-governing communities with auditable moderation and mod elections
It keeps 6 months of posts by default. It's gone after. If something is worth keeping, someone will save it within six months — but not from beyond that.
It's peer-to-peer, and it has no servers. It's privacy sensitive because of that, source IP of any specific public post cannot (easily) be determined.
Actions of moderators are visible to users. No content can just 'disappear', if something gets deleted, you'll know who did it, why they did it, and if you want, how to get it back.
Communities can elect and impeach their own mods by voting. If a mod behaves inappropriately, users can disable that mod locally as well.
macOS Windows and Linux