PDF Seal
A browser-based editor for preparing PDFs for signing. Upload a PDF, place signature fields, then download it or share it with someone else.
Open the live app
PDF Seal does not sign PDFs cryptographically. It adds signature form fields that PDF viewers and e-signing tools recognise, and it can inspect signatures that already exist.
Tech stack
- Frontend: Angular 22 (standalone components, signals, zoneless), NgRx SignalStore, pdf.js
- Backend: Node.js, Express, TypeScript, pdf-lib
- Tests: Vitest
- Storage: none on the server — version history and templates live in your browser (IndexedDB)
Sections
| Section | What it does |
|---|
| Overview | Read-only summary of the document: metadata (title, author…), fields, signatures, stamps, links and comments. |
| Signatures | Place, move, resize and remove signature fields, and save them as reusable templates. |
| Versions | Local history of every upload and edit. Compare any two versions and see what changed. |
| Certificates | Inspect the certificate chain of existing signatures and run an optional trust check. |
Also: Share sends the PDF directly to another browser (WebRTC), ? opens help and an interactive tour, and a browser extension can send PDFs from any page into the app.
Project layout
app/ Angular UI
server/ Express API (+ its tests and scripts)
extension/ Chromium browser extension
All three share the single package.json at the root.
Run, build, test
Requires Node.js 24 (nvm use picks it up from .nvmrc; ^22.22.3 and 26+ also work).
npm install
npm run dev # develop at http://localhost:3000 with live reload
npm run build # build server + UI into dist/
npm start # run the built app at http://localhost:3000
npm test # unit tests (server + Angular); no running server needed
npm run test:e2e # end-to-end tests in Chromium (builds the app first)
The Angular unit tests run in jsdom with every server call mocked, so they work anywhere, CI included. The e2e tests (e2e/, Playwright) build and start the app themselves and drive it in a real browser; the first run also downloads Playwright's Chromium. On Linux, if Chromium then fails to launch, install its system libraries with npx playwright install-deps chromium.
Or with Docker:
docker compose up --build
More commands (coverage, demo sample, extension packaging) are listed in package.json; contributor notes are in AGENTS.md.
Privacy
Documents are processed in memory and deleted after each request. See PRIVACY_POLICY.md.
License
MIT
