How most online PDF tools actually work
When you upload a PDF to a typical online PDF tool, your file is sent over the network to that company's server. The server runs the processing (merge, split, compress, OCR, etc.), saves the result, and gives you a link to download it. The original file may be retained for minutes, hours, or days. Server breaches happen. Backups happen. Honest mistakes happen. The only way to fully eliminate the risk is to never upload the file in the first place.
How PDF Lab works
PDF Lab uses two well-known JavaScript libraries — pdf-lib and pdf.js — to process PDFs entirely inside your browser. The libraries themselves are self-hosted by PDF Lab, which means even loading the page doesn't pass anything through a third-party CDN. When you select a file, it goes straight from your disk into your browser's memory. Nothing is sent over the network. You can verify this yourself: open your browser's DevTools, switch to the Network tab, and use any PDF Lab tool. You'll see no outbound requests carrying your file.
What this means in practice
- ✓Your file is never seen by PDF Lab, Actwise, your network provider, or anyone else.
- ✓You don't need an account, and there's nothing to delete later.
- ✓Once the page has loaded, the tools work without an internet connection — useful in restricted networks or on the go.
- ✓There are no analytics, fingerprinting scripts, or tracking pixels on this site.
Trade-offs we make for privacy
Some advanced PDF features genuinely require a server — for example, large-scale OCR or LLM-based summarization. Rather than break the privacy promise quietly, PDF Lab simply doesn't ship those features. When and if we add server-powered tools, they will be clearly labelled and opt-in, and the homepage promise will continue to apply only to the tools that run locally.