How Firefox’s vertical tabs came to life with a little help from our community

If you’ve ever had more tabs open than you can count, you know the struggle: tiny, unreadable tab titles, constant scrolling, and that moment of panic when you close the wrong one. Enter vertical tabs, a long-requested Firefox feature designed to make tab management and multitasking easier. 

But this wasn’t just something we built overnight — getting it right took time, iteration, and a lot of feedback from our community. I spoke with Ania Safko, the product manager leading the charge on vertical tabs, about how the idea evolved — and how global community voices helped shape every step of the journey. 

A new way to manage tabs

We’re naturally wired to scan lists vertically — it’s how we read, process information, and navigate menus. Yet, browser tabs have traditionally been horizontal, which works fine — until you have more than 10 tabs open. At that point, finding the right tab isn’t just tedious, it’s downright overwhelming and frustrating.

Introducing the sidebar and vertical tabs in Firefox

With vertical tabs, Firefox offers an alternative: tabs stacked along the side of your browser window, making it easier to organize, switch between tabs, and keep track of what’s open. This feature is especially useful for people who juggle multiple tasks and have lots of tabs open, need to remove distractions for deep focus, or just like a cleaner way to manage their tabs.

Recognizing the need for change

Vertical tabs weren’t just a shot in the dark. We’ve had signals of the feature’s value for years — requests in Mozilla Connect, popularity of third-party extensions for vertical tabs, and popular CSS customizations that the community was trying out and distributing. Many power users resorted to using multiple windows to compensate for crowded tab bars. The demand was clear, and we knew we’d disappoint a lot of folks if we got this wrong – so we set out to improve tab management for everyone.

It’s more than just turning tabs sideways

While the concept of vertical tabs sounds simple, making it work seamlessly was a big undertaking. Our core team of one product manager, one UX lead, five engineers (and multiple internal contributors) had to tackle a number of unique design and functionality challenges:

• Balancing the need for a clean and minimalistic tab view with the need to see longer tab titles useful for many tasks.
• Ensuring tabs remained easy to close, mute, and share, even in the minimalistic, collapsed mode. 
• Balancing smart defaults with customizations: offer a useful experience right away while also allowing users to tweak things to their preference.
• Ensuring performant and smooth animations for expanding and collapsing on a broad range of devices and OSs

We also wanted to build something that contributed to a better, more cohesive Firefox experience in the long run. That meant considering how vertical tabs would work with the existing tab management tools and future features, like tab groups.

The Firefox’s community shaped the vertical tabs feature

One of the biggest strengths of Firefox is our user community — and they played a major role in shaping vertical tabs. 

When we released an early version of vertical tabs in Firefox Nightly, feedback started pouring in. Early adopters helped us:

• Improve stability and accessibility by testing vertical tabs on a variety of devices,operating systems, and pre-existing browser settings.
• Polish user experience, by using it in real environments, for diverse and complex tasks, over weeks – something no amount of usability testing can replace.

Like many Firefox features, vertical tabs began as a small-scale experiment. The Mozilla team had been using this feature internally from day one – which helped spot bugs early, refine accessibility, and polish the interface in small but meaningful ways. Once external testing began, community feedback  became even more crucial –  both positive and negative. 

We especially appreciated hearing from long-time sidebar users on Mozilla Connect, who pointed out where the experience didn’t quite meet their expectations or disrupted their workflows. 

One key example: Originally, vertical tabs auto-collapsed when users opened a sidebar panel. While usability testing suggested this would save space, real-world users found this behavior cumbersome. We listened — and changed it.

Another experience shift came from a community discussion around expanding tabs on hover. A user suggestion reignited an internal conversation about the best implementation, leading us to refining existing implementation. The final version looks more polished and saves users extra space, thanks to community input.

Throughout the development, Ania was excited to see strong engagement from the Firefox’s international community. She often found herself responding in Ukrainian and Polish – her two native languages – to gather additional feedback, troubleshoot issues, or help users file bugs. She even jogged her memory of French and Spanish while translating notes from users in Mexico, France, and Colombia. For Ania, it was reassuring to see how much communities around the world cared about Firefox and actively contributed to making it better.  

Balancing different opinions

As with any new feature, opinions were divided. Some users loved the on-hover close button for collapsed tabs; others found it too easy to accidentally click. Instead of making a snap decision, we let the feature sit in Nightly, gathered more data, and are continuing to fine-tune it based on broader feedback.

For us, balancing user habits with innovation is always a challenge. People get used to workflows, and even if a change ultimately improves usability, the initial adjustment period can be tough. That’s why we take an iterative approach — rolling out changes gradually, listening to real-world experiences, and making improvements along the way.

For Ania, this process reinforced the joy of building something that people feel passionate about. Seeing how different users engaged with vertical tabs — even when they had concerns — helped the team craft a better experience, ensuring that solutions met real needs of a diverse global community that chooses Firefox as their daily browser.

Thank you Firefox community

We couldn’t have done it without the community. Every bug report, suggestion and discussion helped make vertical tabs a better experience for everyone. Whether it was through Mozilla Connect, social media or direct feedback, users showed us what worked, what didn’t and what could be improved.

To all of you who shared your thoughts — thank you. Your feedback continues to shape Firefox, and we’re excited to keep building alongside you.

What’s next?

The launch of vertical tabs is just the beginning. We’ll continue refining the experience based on real-world usage and feedback, and we’re excited to see how people incorporate it into their browsing workflows.

If you haven’t tried vertical tabs yet, now’s the perfect time to give it a spin: navigate to Firefox Settings - General - Browser layout and switch the radio button to Vertical tabs. And as always, we’re listening — so let us know what you think!