It is important to distinguish between these two data sources and their missions.
FracFocus serves as the collector and manager of fracking chemical disclosures of the oil and gas industry. It delivers published disclosures to state regulators and it operates a website to help the public see those disclosures and offers a bulk download of the disclosure data. While it started in 2011 as an experiment, disclosures to FracFocus is now required by many states.
Open-FF (this site) is independent of FracFocus, the industry and state regulators. Open-FF adds to the FracFocus data to correct errors and reduce ambiguity, calculate chemical quantities and provide perspective. Data, code and tools generated by Open-FF are open source and available to everyone.