PDFx
A free-floating 2D Canvas for processing multiple PDF files
...Documents appear as horizontal strips of pages, with separate files stacked vertically. Users can rearrange or remove documents before exporting the entire collection as one PDF. The software introduces a backward-compatible PDF extension that preserves the structure of original documents through an embedded JSON manifest. Exported files remain readable in conventional PDF viewers while retaining their organizational information in PDFx. Built with Electron, React, and TypeScript, it supports Windows, macOS, and Linux.