Protect PDF
Real, browser-based PDF password protection isn't available yet — this page explains the technical limitation honestly instead of faking it.
Protect PDF tool
100% Privacy
Files stay strictly on your device. Zero server uploads.
Instant Speed
Local browser WebAssembly & JS processing engine.
Free Forever
Unlimited usage with no hidden fees or watermarks.
How to Protect a PDF with Password
Upload PDF
Upload the PDF you were hoping to protect.
Read the notice
See why real encryption isn't supported yet, and what to use instead.
Start using Protect PDF now – it’s completely free and works instantly in your browser.
Frequently Asked Questions
Is the downloaded file actually encrypted with my password?
There is no download. Real PDF encryption requires implementing the PDF password-security standard (key derivation plus per-object encryption), which pdf-lib — the library this site's PDF tools are built on — does not support writing. Rather than produce a file that looks protected but isn't, this tool tells you that plainly instead of faking it.
What should I use instead right now?
Desktop software such as Adobe Acrobat, or your operating system's built-in PDF/print tools, can apply real password protection today.
Is my file sent to a server?
No. Processing happens entirely in your browser.
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