THE FILES.CO JOURNAL
Notes on PDFs, privacy, and standards.
How the tools work, why your files never leave the browser, and the technical detail that matters.
Fillable PDF forms explained: AcroForm vs XFA
Some PDF forms you can fill anywhere; others demand special software and refuse to open. The difference is AcroForm vs XFA. Here's what that means and how to fill a form in your browser.
Aug 16, 2026 · 5 min readStandardsA PDF is a container, not a sheet of paper
PDFs can carry whole files inside them, in a name tree the page never shows. How embedded files work, why PDF/A-3 exists, and the bug that loses old attachments.
Aug 15, 2026 · 6 min readStandardsHow content stacks inside a PDF, and why 'behind' isn't a layer
A PDF page has no layers panel. It has a painting order, and whatever is drawn last wins. That single fact explains what overlaying one PDF on another can and can't do.
Aug 14, 2026 · 6 min readGuidesWhy scanned PDFs are so big, and how to shrink them
A five-page scan somehow weighs 40 MB. Here's why scanned PDFs balloon, and how to shrink one to a sane size in your browser without uploading it.
Aug 14, 2026 · 5 min readStandardsA PDF has no page size until someone draws one
Page size in a PDF is just a rectangle written into the file. Change that number and the paper edge moves while the content stays put. Here's what actually resizes a page.
Aug 13, 2026 · 5 min readGuidesWhat counts as an annotation in a PDF (and why some of them look like content)
Sticky notes, highlights, links and form fields all live in the same list inside a PDF. Knowing which is which explains why removing them wholesale breaks documents.
Aug 12, 2026 · 5 min readNo spam. Just PDF craft.
Once in a while, a useful note on PDFs and privacy.