A browser-based PDF editor for merging, splitting, compressing, and annotating documents — no upload to a server required.
All PDF manipulation runs in a Web Worker via PDF.js and pdf-lib, so multi-hundred-page documents never block the main thread and never leave the browser.
Large PDFs (500+ pages) caused the UI to freeze when processing ran on the main thread, and users had privacy concerns about uploading sensitive documents to a server.
Moved all parsing/writing into a dedicated Web Worker with a chunked processing queue, and kept the entire pipeline client-side — nothing is ever uploaded.