There is the open source OpenBMC software nowaydays, which is pretty good.
Unfortunately, Supermicro doesn't use it yet for most of their servers. Probably because they sell an extremely expansive license for their own software so you can use the Redfish API.
>>preiss+(OP)
The one vendor mentioned in the comments, AMI, is switching this code base to openbmc. Also it should be noted that often this software is system specific.