It uses a KeePass database and is a self-hosted app in the browser that works perfectly fine on mobile. I have the page up at all times in Chrome on my Android for quick and easy access. The desktop app I have on my home PC. Everything is synced through Dropbox which is the actual storage location for the encrypted database. I have the desktop app set to make backups just in case on my local PC as well. But Dropbox is what they all connect to. I personally love this web app implementation of KeePass much more than anything else like lastpass or other paid services. Been using it for several years now and I've never had an issue. You'll need to grant the web app special access in Dropbox to get it working properly, but it's easy to set up.
EDIT - by "self-hosted" I really mean cached in the browser so nothing is going through the site, it's all local to you after you load the app. Also, this means you can still use it offline if you need to because the Dropbox database is also cached until it can update accordingly when connection is resumed.