Galapagos.dll is not documented (beyond some very cursory xml comments), however it is only dependent on framework assemblies so can easily be referenced and used by whoever wants to. The Galapagos component does provide a bunch of interface stuff not available from Galapagos.dll which at present makes it rather difficult to implement a proper interface.
I’m planning a big update for Galapagos come GH2, more solvers, more functionality, easier repurposing. That’s at least several months away though.