Documents and notes decision
PDF Expert
A capable developer can build a useful web-based PDF editor and annotator using existing libraries and the provided prior-art examples; keep paying for PDF Expert if you need native Apple polish, the integrated Copilot, or Readdle's distribution and support.
Visit website↗Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need — the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship.
What a replacement has to do
- Open and render PDFs in-browser, annotate and edit pages, perform OCR on scans, capture and embed signatures, and export/save modified PDFs.
What it still won’t have
- PDF Copilot: AI-powered assistant to interact with PDFs
- Native macOS/iOS integrations and Apple Pencil-optimized UI
- App Store distribution, reviews, and Readdle brand trust
- Priority support and product polish (continuous native updates)
- Proprietary 'Enhance' (AI-based scan cleanup) and potentially higher-quality OCR tuning
What remains hard
- Brand trust
30 Million Users worldwide
First-year cost
Keep paying
Paying is—cheaper in year one.
On cash alone, building overtakes the subscription at 2 seats.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a browser-based PDF editor using Next.js + React, Postgres, and a small Node/Express backend. Implement: (1) PDF rendering with PDF.js, (2) annotation creation/editing and persistence via REST + Postgres, (3) PDF content edits and page operations using PDF-lib, (4) server-side OCR using Tesseract and attach searchable text layers, (5) signature capture via a canvas component and embedding into PDFs, (6) export/download and basic user sessions (email/password). Out of scope: native macOS/iOS apps, App Store packaging, and a full AI Copilot. Include error handling, input validation, automated tests for API endpoints, and end-to-end tests for the core flows.
How we checked
How the score was reached
- Partly verdict base52
- An open-source build was found+5
- 5 cited sources+3
- Evidence score60
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time — so the same evidence always produces the same number.
How scoring works →Cited sources · 5
Every page the run actually retrieved.
- official productPDF Expert home
- official pricingPDF Expert pricing
- official docsPDF Expert iOS features
- open sourceSteveTheKiller/KillerPDF
- open sourcemrmn2/PdfDing
Integrity checks
What held up, and what did not.
