- It's a free communication and collaboration tool. For this particular use-case though, you could create channels and keep posting URLs in them. Also,there's a set of apps that come pre-installed on Flock, one of them is Shared To-dos. You could alternatively, add each link as a task using this particular app. This way tracking becomes easier.
- @hypothes_is lets you annotate living URLs in real-time with anybody, and the shared annotations(comments) get saved permanently to the page and are always retrievable with the chrome extension https://chrome.google.com/websto... Using @hypothes_is removes the need for a tool outside the browser, it turns your browser into your URL-message-group via the extension. However, this also means that new annotations(comments) only happen within the browser; I like this approach though, it causes those who visit the URL to explain their thoughts per-item, and I believe this leads to more meaningful conversation about the content behind the URL to start with. Other options would be @discourse, @WhatsApp, or http://keep.google.com