Account Surfer is described as 'Quickly switch between accounts and browsers with Account Surfer'. There are more than 10 alternatives to Account Surfer for Mac, Windows and Linux. The best alternative is Choosy. It's not free, so if you're looking for a free alternative, you could try Browserosaurus or Browser Select. Other great apps like Account Surfer are Finicky (Free, Open Source), LinCastor Browser (Freemium), Braus (Free, Open Source) and Browser Fairy (Paid).
Take control of the many browsers that you may have installed on your Mac. Can launch links from just about any application. Uses no resources when idle. Works with just about any browser. Highly configurable appearance lets you choose colors, size, and more.