Questions, answered.

A fast, native PDF app for macOS. Open even very large drawings, mark them up with the full annotation toolset, measure to scale, OCR scans into searchable text, organize pages, and print exactly the way you want. It's built for people who work with big technical PDFs — plans, drawings, submittals — not just reading an e-book.

It's free while RyDF is in alpha. It won't be free forever, but there's no charge during the alpha — grab it and put it to work.

A Mac with Apple Silicon (M1 or later) running macOS 11 Big Sur or later. See Downloads.

Not during the alpha — macOS (Apple Silicon) comes first. Windows and Linux are on the roadmap: the core engine is cross-platform, so they're planned, though a few macOS features (like on-device OCR via Apple's frameworks) will need platform equivalents.

Into the PDF itself. When you press ⌘S, RyDF writes your annotations back into the same file — there's no separate sidecar to keep track of or lose. Reopen the PDF in RyDF later and every markup is still fully editable.

Yes — but use the right save. A plain ⌘S keeps your markups editable in RyDF; other viewers won't display them. To send a drawing to somebody else, use Export ▸ Save a Copy…: that writes real PDF annotations Preview, Acrobat and Bluebeam understand, and tucks the editable version inside so the copy stays fully editable if it comes back to you. See the user guide for which save to use when.

No. Nothing is written until you save. If you'd rather keep the original untouched, use Save a Copy and mark up the copy. Between saves, a lightweight autosave keeps a backup so you don't lose work.

That's the point. RyDF renders pages in tiles and keeps a RAM cache of what you've viewed, so huge multi-hundred-page drawings scroll and zoom smoothly. Files open straight to the first page while the rest loads in the background.

Yes — each opens in its own tab, and switching between them is instant because they stay loaded in the background.

As accurate as your calibration. You set the scale by drawing a line over a known length on the page, and RyDF derives everything from that. Snap-to-geometry helps you land exactly on the drawing's own linework, and scale is stored per page so a set with mixed scales stays correct.

Millimeters, inches or points. You can type math right into measurement fields, and inches accept fractions.

No. OCR runs entirely on your Mac using Apple's Vision framework. RyDF adds an invisible text layer over the scanned image, so the page looks identical but the text is now selectable and searchable. Your document never leaves your machine.

It shouldn't — builds are signed and notarized by Apple, so they open normally. If you somehow hit it on an old build, right-click (or Control-click) RyDF → Open once, or just re-download the latest from Downloads.

RyDF checks GitHub Releases for newer versions and can download and install them for you — on a schedule you set, or only when you ask. You can always grab a build manually from Downloads.

RyDF is a local app. Your PDFs stay on your Mac — it doesn't upload them, and OCR is on-device. The only network calls it makes are to GitHub to check for updates.

Perfect — that's exactly what an alpha needs. Use the feedback form and tell us what you were doing and what happened (a screenshot helps a lot). Feature ideas are welcome there too.