...and Vivaldi had vertical tabs as native functionality before Edge even existed (and about six years before Edge implemented it).
The only other browser (to my knowledge) that had native tabs earlier than Vivaldi was the original Opera browser, which was eventually killed, which in turn led to people leaving the company and creating Vivaldi.
The only other browser (to my knowledge) that had native tabs earlier than Vivaldi was the original Opera browser, which was eventually killed, which in turn led to people leaving the company and creating Vivaldi.