TheGamesDb.net

I would like to replace many of the lower quality box art images with much cleaner higher quality versions, but there doesn't seem to be a way to do this?

Choose game, click "Edit", click "Upload images".

The uploaded images appear on the website but not on emulator frontends.

This tends to be an issue with cache syncing and - depending on the project - should generally clear up within 24-48 hours.