Jack Wallen/ZDNETI’ve been a fan of Firefox for a long time. However, a few years ago, I dropped it as my default browser because I found its tab management lacking. On top of that, the browser was missing some other UI customizations. Plus, it’s been nearly four years since the Firefox developers implemented a major tweak to the UI, which means Firefox is getting a bit stale. That’s why, when the developers of Zen Browser reached out to me, my interest was piqued. Also: 5 Firefox-based, privacy-first web browsers that improve on the originalZen Browser is based on Firefox ESR 128. But for those who don’t know, Firefox ESR is an extended-release candidate, which means it’ll be supported for much longer than the standard release. What Zen Browser does with Firefox is impressive because it brings it almost in line with my favorite browser, Arc. Zen tweaks Firefox by making use of a sidebar but also (and finally) adding better tab management via Workspaces similar to Opera’s. That feature alone makes Zen Browser superior to Firefox (and a worthy option to replace my current default).Zen Browser includes the following improvements to Firefox:A highly customizable UIVertical tabsSplit viewsWorkspaces for improved tab managementCustomizable sidebarZen Glance (similar to Little Arc)OCSP enabledHTTPS only modeZen Mods to add even more featuresWhen you add those features on top of Firefox ESR, you have the makings of a pretty sweet browser. I’ve been using Zen Browser for a while now, and I can’t imagine going back to Firefox. I’m also starting to believe it could easily overtake Opera as my default on Linux.Also: Opera delivers a browser so dynamic it’ll make your friends on Chrome jealousOne really cool feature I’ve been exploring with Zen is the Zen Mode. Through the Zen Mods store, you can install a long list of modifications that help make Zen Browser even better. Some mods are as simple as making your current tab stand out better, while others can be a bit more complicated. I’ve added Zen Mods such as:Drop Shadow – adds a drop shadow to the website view panel.Better Active Tab – adds a bright line next to the active tab.Better Letterboxing – a theme-friendly rounded letterbox for the UI.Cleaned URL bar – cleans up the Zen Browser URL bar.Floating Toolbar – detaches the toolbar from the edge of the browser.Super URL Bar – several tweaks to the URL bar More