Is there any decentralized software similar to MusicBrainz or booru-style image boards for collaboratively tagging various media files (music, movies, books, images, etc.) without the need for a centralized database? I'm looking for something where users can contribute metadata and tags in a peer-to-peer fashion.

While I understand that such a decentralized system may result in messy or unreliable metadata due to the lack of curation, I'm willing to accept that trade-off. Sometimes, having any metadata available, even if it's imperfect, is better than having no information at all about a particular file, especially when I don't remember the details myself.

I'd be grateful if anyone could recommend existing software or projects that fit this decentralized, collaborative tagging approach, even if it's a proof-of-concept or works for only a specific media type like music or images. The key requirement is the absence of a central database or authority, with metadata being crowdsourced and distributed across a peer-to-peer network.