I'm building MLSync.io [1], an ETL platform that helps real estate companies easily access and use MLS (Multiple Listing Service) property data without the technical headaches. I've originally developed this for internal use in an IDX startup, but the complexity of RESO synchronization led me to spin it off into its own dedicated tool.
Looks good. I created propertywebbuilder.com as an open source real estate website builder some years ago. Had wanted to do something similar to mlsync next but never got round to it.
[1] https://MLSync.io