QuickFIX is an open-source FIX messaging engine written in C++, created by Oren Miller and a small team from ThoughtWorks, alongside Jim Downs of Connamara Systems.
Launched in 2002, there are several implementation variants of the engine, including:
– QuickFIX/J, a Java open-source implementation.
– QuickFIX/n, a C# and .NET open-source implementation.
– QuickFIX/Go, a Go open-source implementation.
You can find out more about all the implementations, and access the source-code at quickfixengine.org.