A PDS? Here: https://blog.bront.rodeo/setting-up-your-own-pds/

Want your own AppView so you can have nekusar.net and post your messages and people on BSky see it ? https://github.com/blacksky-algorithms/atproto

ActivityPub zealots would do well to calm down for one second, this can't be good for your heart man.

Well actually, that's not what an AppView is for.

If you just want to post messages on your website that get syndicated to BlueSky (as blog post links or full threads or whatever) you could have your website server make API calls to your PDS (whether that's self-hosted or not).

If you're talking about building your own custom BlueSky app, "AppView" is not synonymous with "viewer app"; basically it's an "AppView" because it provides a "view" of the network necessary to power an end user "app". I.e. it holds a copy of every single post, repost, and like, so you don't have to. Your custom app would simply make requests to the logged-in user's PDS, which routes most of those requests to that user's preferred AppView.