A small tool for an annoying file format
fuckpdf does the boring things people actually need to do to a PDF (merge it, split it, rotate it, number it, crop it) in the browser, immediately, for free.
Why it exists
The usual PDF sites take a file you probably should not hand to a stranger (a contract, a payslip, a scan of your passport), upload it to a machine you know nothing about, put you in a queue, and ask you to sign up somewhere around the third page. None of that is required to rotate a page. The work is arithmetic, and your computer does arithmetic.
How it works
Every tool is a pure step that takes bytes and returns bytes. Two engines do the work: PDFium, compiled to WebAssembly, for rendering pages, and pdf-lib for reading and writing the file structure. PDFium loads only when a tool needs it, in a Web Worker, so the interface stays responsive and nothing large downloads until it has to.
What it will not do
It will not edit existing text inside a PDF, recover a password you do not have, or run anything that needs a model or a server. Where a conversion loses fidelity, the tool says so before you run it instead of after.