Download Notifier is a free Chrome add-on developed by ehaagwlke. It is designed to provide users with a desktop notification when their downloads are finished. This add-on is now open-sourced and can be found on GitHub.

With Download Notifier, you have the option to play a sound when your download is complete. Additionally, you can choose whether or not the default download shelf should be displayed. This add-on also supports multiple notification cards, making it easy to keep track of your downloads.

One of the main features of Download Notifier is the ability to disable the download shelf and instead receive a badge notification while something is downloading. While there is no progress bar available at the moment, you can easily find your completed downloads with just one click.

Please note that there are a few features that may be implemented in the future, such as an animated browser action icon to show downloading progress and a "OPEN" button on the notification card. However, these features are dependent on Google's approval.

Overall, Download Notifier is a useful Chrome add-on for those who want to be notified when their downloads are finished. It offers customizable options and a simple interface, making it easy to manage your downloads.