The best alternatives to Kitab are Raindrop.io, Trove, and Bookmark OS. If these 3 options don't work for you, we've listed a few more alternatives below.
Bookmark OS uses Mac / Windows inspired UI to help you organize your bookmarks. Access anywhere. Bookmark OS is a responsive website. Use it on your laptop, phone, or tablet.
Linker is a lightweight and simple app to help you save, organise, and share your links. We provide a web app, iOS and Android apps and nice browser extension that let you quickly save your links. No more flipping through a bookmarks folder in your browser.
Tab Space is a Safari extension which can: 1. Save or restore your browsing tabs at 1 click (like OneTab). 2. Mark your saved tabs with #tags as filters. 3. Provide some useful shortcuts for Safari such as "Close left tabs". Note: Safari 12.1 or later required