Did you even look at the WEX platform I mentioned above?
In answer to your question here, MM's while use a variety of platforms. Some examples would be
Actant
Actant Trading Software
BTS
BTS Edge • Up Your Options Trading Game | Blue Trading Systems
Vela
Global Leader in Data and Execution Technology - Vela | Vela (tradevela.com)
These are three that I am familiar with and they will be a substantial amount of money.
I would guess the larger MM's would use proprietary software.