Encrypt your PDF with a password to prevent unauthorized access.
Your file stays private. Password encryption is applied locally in your browser using pdf-lib Γ’β¬β no uploads, no servers. Set a password and download your protected PDF instantly.
Secure your sensitive documents by adding a password with our protect tool, keeping your files safe from unauthorized access. To password protect PDF online free, upload your file, enter a strong password, and download the encrypted version instantly. The encryption is applied entirely in your browser using pdf-lib, so your document never leaves your device and no data is transmitted over the network. This is essential for protecting confidential business reports, personal financial documents, legal contracts, or any PDF that contains sensitive information. Once protected, the password must be entered to open the file, giving you full control over who can view it. Encrypt PDF file securely with our fully client-side tool Γ’β¬β no data transmission, no server storage, complete privacy guaranteed.
The protect tool adds a password to a PDF so no one can open it without entering that password first. Encryption runs entirely in your browser with pdf-lib, which means the file never leaves your device and nothing is uploaded to a server. In a few seconds an open document becomes one that stops strangers at the door, and you decide who gets in and who does not.
PDFs travel further than most people expect. An attachment gets forwarded, a shared folder link leaks, a chat chain grows, and every hop widens the circle of people who can open the file. Password protection puts a barrier in front of the content itself, so even a file that lands in the wrong hands stays unreadable without the key. Contracts, financial statements, tax returns, medical records, and anything with personal details are the obvious candidates, but a confidential draft or a pricing sheet benefits just as much from a quick lock before it is emailed around the office.
The tool applies the same password as both the user password and the owner password, so the document is locked for viewing and for editing alike. If the password is lost, no service can recover it, which is why you should keep a copy somewhere safe before you replace the original file on disk.
It helps to be clear about what a password can and cannot do. The password controls opening the file, so anyone you share it with can still copy, print, or forward the PDF afterward. Protection is a strong first layer against casual access, not a substitute for careful sharing, which is why the password deserves its own delivery channel.
Because encryption happens inside the browser, confidential documents are never transmitted across the network. There is no server holding a copy, no upload log to worry about, and no account required to keep track of what you have processed. This is the same client-side architecture used across every tool on the site, so sensitive paperwork is handled as if you ran the operation on your own machine rather than trusting it to a stranger's computer.
That design also keeps the workflow simple for the recipient. A protected file is fully self-contained and opens in any ordinary PDF viewer once the password is entered, with no special software required on either end of the exchange.
Pro tip
Send the password through a different channel than the file. If the PDF goes out by email, share the password by phone or in a separate message, so a single compromised inbox does not expose both the document and its key.
The free tier handles PDFs up to 10 MB with a short wait before each run. Premium subscribers can protect files up to 100 MB, process whole batches at once, and skip the wait entirely, which makes it practical to lock down large reports or an entire folder of contracts in one sitting.