The nimble.directory alternative no one asked for, that I felt like making anyways. Check it out at nimpkgs.dayl.in.
In it's current form packages for nim are managed by a single JSON file.
A web UI is available at nimble.directory(repo).
But, there are some outstanding issues that have affected even my own packages.
This site is client-only, powered by karax and styled with unocss. This makes it trivial to deploy with Github Actions.
Logos in site/img by The Nim Programming language used under CC BY 3.0.