And a browser extension that suggests open-source alternatives based on the current page's URL: https://github.com/nileshtrivedi/better

It also allows you to submit new recommendations via the extension itself which submits a pull request to its GitHub project.

What's interesting is that: the extension lets you subscribe to multiple sources for recommendations (much like adblocking filters). This means that curation of alternatives can be done by people YOU trust and could incorporate criteria other than license: Ethical, Low-priced, Locally produced, Sustainable etc.