I've built a tool to track downloads counts for releases of repositories:

https://repostats.yolo42.com

I run two Open-Source projects and we host our releases on Github. Github maintains a total counter for downloads but there is no way to track downloads per day.

It is pretty basic and bare-bones but works. It tracks downloads per asset, which gives you a good insight into adoption of your product.

It requires you to Sign in with Github only to work around the rate-limits of Github API. It only needs read access on basic profile data.

You can add up-to 3 repositories to track and it is completely free.

Let me know what you think!