An extension of the traditional PDF standard

I'm the author of this project, someone else posted it on my behalf, let me explain my story:

My bank requested 17 PDF documents for a mortgage application.

I got tired of opening and closing files and keeping track of things. So I decided to merge all files into a single, long PDF and send it to my bank, but that caused even more confusion.

To solve this issue, I came up with an idea: what if I could extend the standard PDF structure by embedding custom JSON metadata to indicate where files start and where they end?

I called it `.pdfx`, but it's simply a backwards-compatible PDF file, that when opened with traditional PDF viewers (Chrome, Acrobat), it renders as a regular, continuous document. But when opened in the PDFx runtime, a react-based viewer I built, the app parses the metadata coordinates and reconstructs a 2D free floating canvas, where the pages of a file extend horizontally, while files themselves grow vertically.

This view allows for a greater spatial understanding, batch processing, and a pleasant drag-n-drop user experience. Plus, additional support for SVGs, PNGs and technical drawings that are converted into PDFs when dropped onto the app.

Your feedback would be highly appreciated.

PDF already has the notion of portable collections (PDF 2.0 section 12.3.5). As far as I can determine this is very similar to what you do except that your pdfx format won't be supported by (major) PDF viewers/libraries.