Why does the extension ask for permission to read and change data on a number of websites?

Beermoney balances works by running a small amount of javascript on specific sites that reads you balance and saves it locally. Because each of these scripts are tailored to only run on the site they’re needed the app needs a separate permission for each site. These all get lumped together as a “number of websites”. There’s no separate permission between reading and writing so even though the extension doesn’t change any data it still gets given permission.

How can I know that the extension isn’t going to do anything bad?

You can see the full code for the extension here.

How can I get a new site added?

Use the feedback form on the main page, leave a comment on Reddit or contact me on Twitter. If you know your way around web development you can submit a pull request with the new site on Github

How does this extension make money?

Right now it doesn’t.

When will it be available on Firefox?

I’ve done some of the work to make it available on Firefox but the last submission was rejected. I’m not planning to try again soon.