Notes on PDFs and privacy

• August 2026What actually happens when you upload a PDF to a converter siteThe file lands on a disk you do not control, gets handed to a command-line program, and waits for a cleanup job. Here is the whole path, including the bug that keeps turning up along it.
• August 2026How browsers got good enough to edit a PDF without a serverTyped arrays, canvas, workers, and one stubborn Mozilla project. The pieces that made the server unnecessary arrived one at a time, and nobody announced when the line was crossed.

What is coming

Roughly in the order we expect to write them:

• Reading a PDF file by hand: what is actually inside one
• Why rotating a page should never turn it into an image
• The command-injection bug in open-source PDF tools, and how to avoid the whole class of it

If one of those is the reason you came here, say so on the contact page and it moves up the list.

If you wanted the short version

Some of this ground is covered elsewhere on the site, in fewer words. How it works walks through what happens to your file, the guides are step-by-step rather than explanatory, about explains why the site has no server, and the FAQ answers the things people actually write in about.