The online world of 3rd strike began in 2007 with the successful emulation of CPS-3. It was originally played on MAME's Kaillera, and then 2DF and GGPO.
History of 2DF / Supercade:
2DFwas created in 2008 by Damdai. Damdai is SSF2T player from USA and a programmer. 2DF ran on FBA emulator. It had Kaillera's netcode. 2DF supported many games, but was mostly known for fighting games. In January 2010, Damdai announced on 2DF forums that replays are slowing down the server and that he'll switch to a web browser client. The new client was renamed to "Supercade". 2DF / Supercade lost its popularity at this time. Most people didn't like the new web based client. It didn't include some key features 2DF had. On October 27, 2010, Damdai brought back the old server based client that 2DF had. However, at this point most players already moved to GGPO which also had superior netcode. In October 2014, Damdai decided to close Supercade. He released a statement: "I've spent a lot of money keeping it running over the years, long after I lost interest in the project, and I don't want to do that anymore."
On 23 August, 2011, 3rd Strike Online Edition has been released on PS3 and Xbox 360.
In 2014, FightCade was released. It had the same emulator and netcode as GGPO. Shortly after, GGPO was DDOS attacked and has since been down indefinitely.
The online world for 3rd Strike now 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 relies heavily on reactions and timing. Any form of online play has slightly different timing than actual Arcade cabinet or offline 3rd Strike Online Edition. Even offline CPS-3 emulation has slightly faster speed than when played on original hardware because that's how emulation works.