Arc has a feature called Boosts that allows you to customize any website with custom CSS and Javascript. Since running arbitrary Javascript on websites has potential security concerns, we opted not to make Boosts with custom Javascript shareable across members, but we still synced them to our server so that your own Boosts are available across devices.
We use Firebase as the backend for certain Arc features (more on this below), and use it to persist Boosts for both sharing and syncing across…
