Help & User Guide
Papi processes PDF files using a pipeline of rules. You drop in a PDF, reorder pages if needed, apply any combination of operations, watch a live preview update, and export a clean new file. Your original is never touched. This guide covers every part of the app.
Quick Start
- Open a PDF — drag a PDF file onto the Papi window, or click the open button to use the file picker.
- Reorder pages (optional) — drag page thumbnails in the left panel to rearrange them. The order you set is the order written to the output.
- Add rules — click Add Rule and choose an operation. Add as many as you need, in any order.
- Check the preview — the centre panel updates immediately as you adjust settings. Scroll the page thumbnails to see indicators for each rule.
- Export — click Export, choose a destination, and Papi writes the new file. Your original is unchanged.
The Page Panel
The left side of the window shows every page as a thumbnail. Drag thumbnails up or down to reorder pages before exporting. The order shown here is the order in the output file.
Thumbnails also show visual indicators when rules are active:
- Pages targeted by a Delete Pages rule show a red overlay with a trash icon
- Pages outside an Extract Pages range are dimmed
- Pages targeted by a Rotate Pages rule display a direction arrow
This means you always know what the output will contain before you export a single byte.
Rules Reference
Rules are applied in order from top to bottom. Click Add Rule to insert a new one, drag to reorder, and click × to remove. You can use the same rule type more than once.
Page Manipulation
Rotate Pages
Rotates pages by 90°, 180°, or 270°. You can rotate all pages at once, or specify a page range (e.g. pages 3–7 only). Useful for fixing scanned documents where some pages came out sideways.
Crop Margins
Trims a specified amount from each edge of every page. Enter values in points for top, right, bottom, and left. Use this to remove scanner borders, excessive whitespace, or pre-printed margins.
Extract Pages
Keeps only the pages you specify and discards the rest in the output. Enter a range like "1–5" or individual pages like "1, 3, 7". The original document is not modified — the output file simply contains fewer pages.
Delete Pages
Removes specific pages from the output while keeping all other pages. Enter the page numbers to remove (e.g. "2, 5–8"). The opposite of Extract Pages.
Annotation
Add Page Numbers
Stamps a page number on every page. Configure position (top-left, top-centre, top-right, bottom-left, bottom-centre, bottom-right), font, font size, colour, and the starting number. You can offset the start value — for example, start at page 3 if the first two pages are a cover and a blank.
Stamp Header
Overlays a line of custom text at the top of every page. Configure the text content, font, size, colour, and horizontal alignment. Useful for adding "CONFIDENTIAL", a document title, or a client name.
Stamp Footer
Same as Stamp Header, but placed at the bottom of every page.
Watermark (Text)
Overlays text diagonally across every page, or at a fixed position. Set the text, font, size, colour, opacity (0–100%), and orientation. A lower opacity like 15–30% is typical for watermarks that sit behind page content.
Watermark (Image)
Overlays a logo or graphic on every page. Choose the image file, set the position, scale the size, and adjust the opacity. Supports PNG files with transparency for clean logo placement.
Metadata
Set Metadata
Writes document metadata into the output PDF: title, author, subject, and keywords. This data is visible in Finder's Get Info and in PDF readers' document properties.
Strip Metadata
Removes all embedded metadata from the PDF in one step. Use this before sharing a document externally to prevent author names, company names, or revision history from travelling with the file.
Output
Compress
Reduces the file size of the output PDF. Choose a quality level:
- Screen — smallest file, suitable for on-screen reading and email (72 dpi images)
- Ebook — a balance of quality and size, suitable for digital distribution (150 dpi)
- Printer — higher quality for desktop printing (300 dpi)
- Prepress — highest fidelity for professional print output (300 dpi, colour-managed)
An estimated size reduction badge appears below the preview so you know what to expect before you click Export.
Flatten
Merges interactive form fields, annotations, and comments into static page content. After flattening, the fields can no longer be filled in or edited. Use this before sharing a completed form to prevent any further changes.
Protect
Sets an owner password on the output PDF, which locks it against further editing, printing, or copying in PDF readers that respect document permissions. Set a strong password and keep a record of it — Papi cannot recover a password once set.
Live Preview
The centre panel shows a full-size preview of the currently selected page with all active rules applied. It updates the instant you change any setting — rotate a page and watch it flip; add a watermark and watch it appear; delete a range and see the page count update.
The one exception is the Compress rule: compression happens at write time. For that rule, Papi shows an estimated file size reduction badge instead of a visual preview.
Presets
Papi ships with built-in presets for common jobs: compress for web, strip metadata before sharing, stamp with page numbers, and archive-quality output. Click a preset to load it and apply it immediately to your document.
To save your own preset, build a rule stack you want to reuse, click Save Preset, and give it a name. Your custom presets appear alongside the built-in ones and persist between sessions.
Your Original Is Always Safe
Papi never modifies your source file. Every export reads from the original and writes a brand-new file to the destination you choose. No matter how many times you export or what rules you apply, the file you opened remains exactly as it was.
Tips & Tricks
- Combine Flatten + Protect for final delivery. Flatten locks in form fields; Protect prevents editing. Stack them both for a secure final document.
- Use Extract Pages to split a large PDF. Run Extract Pages twice on the same source — first keeping pages 1–10 (export to "Part 1.pdf"), then keeping 11–20 (export to "Part 2.pdf").
- Place page numbers after a Crop rule, not before. If you crop the margins first, the page number is stamped in the correct position on the cropped page, not hidden behind the cropped area.
- Use a low opacity for watermarks (15–25%). This keeps the watermark visible enough to deter copying while still allowing the page content to be read comfortably.
- Preview each page in the thumbnail panel. Click through page thumbnails to check that every page looks correct, especially when using page-range rules like Rotate or Delete.
Frequently Asked Questions
Does Papi support password-protected PDFs?
Papi can open user-password-protected PDFs — you will be prompted to enter the password to unlock it. Owner-password-protected documents (where editing is restricted but reading is allowed) can also be opened and processed.
Can I process multiple PDFs at once?
Papi is designed for single-document processing with a live preview. For bulk operations across many PDFs, run each through Papi individually or use a saved preset to apply the same rule stack quickly.
Why is the preview slightly different from the export?
The preview renders at screen resolution for speed. The exported file is written at full document resolution. Minor rendering differences in fonts or thin lines are cosmetic and don't affect the output.
Can Papi merge multiple PDFs into one?
Not currently. Papi works on a single PDF at a time. Merging multiple documents is not yet supported.
Troubleshooting
The preview doesn't update after I change a setting
For most rules the preview updates instantly. The Compress rule is the exception — compression happens at export time. For other rules, try clicking on a different page thumbnail and then back to force a refresh.
Export produces an unexpectedly large file even with Compress
Compression works best on PDFs that contain raster images (photos, scans). PDFs made up of vector graphics or text only may not compress significantly. Try the Screen preset for the most aggressive reduction.
I set a password with Protect but now I can't remember it
Papi has no way to recover PDF passwords. Re-export from your original (unprotected) source file and set a new password — this is why Papi never modifies the original.