twiBook is an alternative to the bookmarking experience on Twitter.
You can create bookmarks from tweets by copying the link to any tweet you find important or interesting so that you can return to them for future reference.
To ease the stress of having to fully depend on the platform. twiBook has a Chrome extension that makes it easier for you to bookmark any tweet without leaving Twitter.
Although, the only limitation is that you won't be able to get tweet previews for any tweet you bookmark with the extension. In the future, you should be able to generate previews from the twiBook dashboard if you want to.