Usually, when it comes to playing SNES games online with multitap support, most people opt for using the popular emulator Snes9x, in conjunction with compatible frontends like RetroArch or Fightcade, with other emulators like BSNES typically lacking the necessary support to make them a viable alternative.
However, over the last 12 months, we've seen some promising new developments, with an individual named HeatXD unveiling a special fork of the BSNES emulator last year, integrated with GekkoNet (a P2P Rollback Game Networking SDK), which aims to make playing multiplayer titles online a little more convenient and "robust".
HeatXD released the initial build (V1) on GitHub last July, featuring the ability to play a whole host of multiplayer games with netplay enabled, but has since returned with a second build (V2) this past weekend, introducing multitap support. This means it is now possible to play with up to five players on games that originally supported the option, including titles like the 1997 Japan-exclusive Bomberman game, Super Bomberman 5.
In addition to that, the new update also includes improvements to "session stability" and spectating, some fixes for pre-existing crashes, and a redesign of the netplay setup window to make it easier to understand.
Much like the previous release, there are a few disclaimers to bear in mind. For instance, the developer encourages players to have the same version of the game installed and not to change any settings during netplay, as both may cause players to desync.
It is currently available to download here for Windows, Linux, Mac, and freeBSD, but HeatXD anticipates there could be issues with broken rendering on the Mac build, based on his own experiments on his M1 Mac.