PDFx is an open, backwards compatible extension of PDF that bundles many documents into a single file, plus a minimal desktop viewer for macOS, Windows, and Linux.
The files produced are fully valid PDFs: open them anywhere and every page shows in sequence. Open them in PDFx and it splits back into the original documents. Plain single PDFs work as they are.
Drag and drop .pdf files, images or folders anywhere in the window. Each document renders as a horizontal strip of pages, and documents stack vertically. Reorder or remove them, then Export PDF to save the whole collection as one file.
See SPEC.md for the format. It is short: the entire trick is one embedded JSON manifest.
Built with Electron, Vite, TypeScript, and React. PDF rendering by pdf.js, assembly by pdf-lib.
yarn # install
yarn dev # run in development
yarn dev:web # run on the web
yarn build:mac # build:win for windows, build:linux for linuxThe AI assistant needs a provider API key: copy .dev.vars.example to .dev.vars, and set your key (Google, Anthropic, or OpenAI).
MIT