L-05 · Products
PDFzdarma.cz
PDF tools in the browser: merge, split, watermark, metadata. Files never leave the computer.
- Role
- Product, client-side PDF logic, UX and performance
- Year
- 2025
- Stack
- Vue.js · Vite · pdf-lib · PDF.js
Problem
Online PDF tools usually want the file uploaded to their server. For contracts, invoices or personal documents that is an unnecessary risk.
Solution
All processing runs in the browser: pdf-lib and PDF.js, with the heavy work in a Web Worker so the interface does not freeze. The file never leaves the user’s computer; the server only delivers the static application.
Documents locked only with an empty password (permission restrictions) are unlocked locally; real passwords are never cracked. Compression rejects unsupported or oversized content before it starts rendering.
Outcome
PDF tools that are safe for sensitive documents, because they have nowhere to send the data.