Watermark PDF. Confidential Text Stamping.
Stamp confidential text, logos, or diagonal markings across all pages of your PDF. FastPDF applies watermarks locally in your browser for maximum privacy.
The text will appear diagonally across every page in light gray.
Drag & drop PDF to add watermark
Stamp confidential text diagonally across all pages.
Funded by Humans, Not VCs.
Why is a top-tier PDF tool completely free? Because we engineered it using WebAssembly. Every computation, extraction, and cryptographic signature happens entirely within your browser using your own computer's native CPU power.
Do you know what that means? Our server cost is practically $0. Since we don't pay massive monthly hosting bills to compute your files, we believe it's a moral obligation not to extract heavy subscription fees from you.
We proudly reject venture capital, we block intrusive trackers, and we despise auto-billing credit card traps. If FastPDF just saved you from a frustrating corporate paywall today, consider buying us a coffee. Your donation keeps our basic routing server online for the next person in need.