Every year, Crossref releases a full public data file of all of our metadata. This is partly a commitment to POSI and partly just what we do. We want the community to re-use our metadata and to find interesting ends to which they can be put!
However, we have also recognized, for some time, that 170GB of compressed .tar.gz files, spread over 27,000 items, is not the easiest of formats with which to work. For instance, there’s no indexing capacity on these files, meaning that it is virtually impossible simply to pull out the record for a DOI. Decompressing the .tar.gz files takes a good three hours or more even on high-end hardware, without any additional processing.