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.

Why Does My PDF Signature Show as Invalid or Not Verified?

A PDF you signed opens with a red 'signature invalid' banner. Here's what that warning actually means, the four usual causes, and how to check a document before it ever leaves your device.

David Carrero · Sep 25, 2026 · 6 min read

GUIDES

Why Do Fillable Form Fields Disappear When You Print or Save a PDF?

Sep 23, 2026 GUIDES

Why Does My PDF Open but Show Blank White Pages?

Sep 21, 2026

Latest

Guides

Why Is My PDF Blurry After Compressing It?

Compressed a PDF and now the text or images look soft and pixelated? Here's what actually causes the blur, and how to get a smaller file without ruining it.

Sep 17, 2026 · 6 min read Guides

How to Convert PNG or JPG to WebP for a Faster Website

Heavy PNG and JPG images are slowing down your site. Convert them to WebP in your browser, keep the quality, and cut page weight in minutes.

Sep 15, 2026 · 6 min read Guides

Editing and Signing PDFs on iPad with Apple Pencil

Your iPad can handle real PDF work — signing, rotating, cropping — right from Files or Safari, with Apple Pencil, and without a single upload.

Sep 11, 2026 · 6 min read

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Once in a while, a useful note on PDFs and privacy.

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