The online world of 3rd strike began in 2006 with the successful emulation of CPS-3 and then the rise of GGPO. Since then the game has been released as "Online Edition" on PS3 and Xbox 360 by Capcom. In 2014, a different program with the same emulator as GGPO was created and was called FightCade. Shortly after, GGPO was DDOS attacked and has since been down indefinitely. Since then, the online world for 3rd Strike mostly consists of FightCade and Online Edition.
It must be noted that 3rd strike is an old game released in 1999 on arcade cabinets which also relies heavily on mechanics and timing. Therefore any form of online play has slightly different timing than actual Arcade cabinet or offline 3rd Strike Online Edition.