PDF Stamp — local & private PDF annotation

Add text anywhere on any PDF, draw or type a signature, and export the edited file — entirely in your browser. The app is a static site: PDFs are opened, rendered, modified, and downloaded locally and are never uploaded anywhere.

Features

• Open any PDF (file picker or drag & drop)
• Place text anywhere on any page: 8 bundled fonts (sans / serif / mono / handwriting), any size, any color; placed text becomes real, selectable text in the exported PDF
• Signature stamps: draw with mouse/touch/stylus or type your name and pick a font + color, then save as a named stamp (kept in browser localStorage; available across sessions)
• Multi-page, zoom (buttons, +/-/0, or Ctrl/⌘+wheel around the cursor), move/resize elements, undo/redo, keyboard nudge
• Download the edited PDF at any time — pages left untouched stay exactly as they were
• Handles pages with any /Rotate (0/90/180/270°) — placed content appears upright

Cross-platform

Works wherever a modern browser runs — Linux, Windows, macOS, tablets. The "desktop" story is simply opening the published web app.

Privacy

• No backend, no analytics, no file uploads: everything is processed in the browser via JavaScript (pdf.js for rendering, pdf-lib for writing).
• Even a published instance (static hosting on GitHub Pages / Netlify / your own server) cannot receive your documents — the code never sends them.
• Stamps/signatures you save stay in your browser's localStorage.

Development

npm install
npm run dev      # dev server at http://localhost:5173
npm run test     # vitest: coordinate math, pdf.js cross-check, e2e export tests
npm run build    # production build in dist/
npm run preview  # serve the production build

How placement works (for maintainers)

• Elements are authored in display space: origin at the displayed page's top-left corner (i.e. after /Rotate is applied), y downward, in PDF points — the same coordinates a pdf.js viewport at scale = 1 reports.
• At export time src/lib/coordinates.ts maps display points to PDF user space per page rotation; content is drawn with rotate: degrees(R) so it appears upright. This mapping is unit-tested against pdf.js's own convertToPdfPoint on all four rotations (src/lib/pdfjs.test.ts), and text/stamp placement is verified end-to-end in Node (src/lib/export.test.ts).

Deployment

npm run build produces a fully static site in dist/. Deploy it anywhere:

• GitHub Pages: the included workflow (.github/workflows/deploy.yml) deploys on every push to main (enable Pages → "GitHub Actions" in repo settings once).
• Netlify / Vercel / Cloudflare Pages: build command npm run build, publish directory dist.

Font licenses

Bundled fonts (see src/assets/fonts/):

• Noto Sans / Serif / Mono — SIL OFL (OFL-Noto.txt)
• Great Vibes, Shadows Into Light, Indie Flower — SIL OFL (OFL-*.txt)