You have landed on the developer page for the catalog. If you wish to see and use the actual catalog, please go to https://lwcvl.github.io/RudolfGeyerCatalog/
Please be advised that although the catalog has grown to its total number of entries, it is still lacking certain details. More work may be expected in the coming years.
For a full description of the working of this web app, please see my book 'Among Digitized Manuscripts', to be published by Brill late 2019. In essence, this code can be easily adapted if you made a bibliography in Zotero.