I have been using a self-hosted Seafile[0] instance since 2014 hosted on my Linux server. It's written in Python[1]. I have never had an issue with it. I sync to my desktops, laptops, phones, etc. It works on all major platforms. It has an online browser just like Dropbox too, supports link sharing, WebDAV, etc. Its server-side storage is based on git[2].

I was really impressed with all the upgrades throughout the years. The upgrade scripts that come with their installations which I run on my Linux box are clearly labelled (e.g. 5.1_to_5.2.sh) and run successfully without giving me random obscure messages that you might sometimes expect.

I recommend people check it out to see if it could work for you.

The only downside really is that since it's git-based storage, you can't just specify "this is the directory I want to serve", rather you have to upload everything via Seafile and it will write it out in its git filesystem (which means it's duplicated if you already have a copy on your filesystem.) This is in contrast to OwnCloud[3] I think, which will let you access/serve remote files from their original location.

[0] https://www.seafile.com/en/download/

[1] https://github.com/haiwen/seafile

[2] https://manual.seafile.com/develop/data_model.html

[3] https://owncloud.org/