Feb 9, 2026 5 min read#privacy#webassembly
Why every modern PDF tool should run locally — and how ours does
A behind-the-scenes look at how PNG on PDF processes everything in your browser and why that’s safer, faster and cheaper.
Most “free” PDF sites silently upload your files to a server, run a binary, and hand back the result. That worked in 2010. In 2026, browsers are fast, WebAssembly is everywhere, and there is no good reason to ship a private contract over the internet just to add a signature.
What runs in your browser
- pdf-lib for creating, merging and editing PDFs.
- pdfjs for rendering pages to high-resolution images.
- Tesseract.js for on-device OCR.
- JSZip for batch ZIP downloads.
All of this is loaded once, cached for offline use, and runs against the in-memory bytes of your file. There is no upload, no queue, no worker pod somewhere in us-east-1.
What you get
- Privacy: your contracts, IDs and medical scans never leave your laptop.
- Speed: instant for most documents — no upload progress bar.
- Offline: open the PWA on a plane and the tools still work.
- Sustainable free tier: zero per-conversion server cost means we can offer it forever, without ads inside the editor.
That’s the philosophy behind PNG on PDF. Try a tool — your file never moves an inch.