We host discussion and development of specifications for interoperability.
These specifications mostly cover low-level desktop issues, such as identifying file types, launching applications, and exchanging data between applications and desktops. They are often called 'XDG' specifications, as an acronym for the Cross-Desktop Group.
freedesktop.org is not a formal standards body, and is not in itself a platform; we do not have a compliance test nor a certification.
Anyone is free to use and implement the specifications on this site; the specifications page explains how to propose changes and existing specifications, or entirely new specifications.