Privacy & trust ·
Client-side vs server-side PDF tools
ihatepdf popularized “no upload” PDF tools. iLovePDF and Smallpdf explain HTTPS encryption and hourly file deletion. Sejda offers a desktop app for offline work. PDFTwin combines both models — here is how to choose.
9 min read
Client-side (browser) processing
Merge, split, rotate, compare, sign, remove pages, images-to-PDF, PDF-to-JPG, text extract, and OCR run with pdf-lib, PDF.js, or Tesseract.js in your tab. Verify in DevTools: no file bytes hit our servers.
- Best for: NDAs, HR records, unreleased financials, compare review
- Trade-off: very large files can stress browser memory
- Similar philosophy to ihatepdf; PDFTwin adds Compare as a focus tool
Server-side processing
PDF → Word/Excel, compress, watermark, lock/unlock, extract pages, and image convert/resize need heavier engines. Files upload over HTTPS, process in memory, and are discarded after the response — like iLovePDF’s documented two-hour max retention, but PDFTwin does not keep files for later re-download.
- Best for: layout-heavy Word export, strong compression, batch image convert
- Free tier: 50 MB files, 3 Word/Excel exports/day, merge up to 5 PDFs
- Pro: 200 MB files, unlimited exports and merge batch
What about PDF24 and Sejda?
PDF24 funds free web tools with ads and offers an offline Creator. Sejda’s web tier limits free tasks but provides a desktop app where files stay local. PDFTwin is web-first with a clear split: organize locally, convert on server when quality matters.