Password-protecting a PDF prevents unauthorized users from opening, copying, or printing your document. This guide shows you how to add strong encryption to any PDF for free — without uploading it to any server.
Navigate to pdfeditor.onl/protect-pdf. No account, no installation — the tool runs entirely in your browser.
Click the upload area or drag your PDF onto the page. Your file stays in your browser's local memory at all times — it is never transmitted to a server.
Enter a user password (required to open the document) and optionally an owner password (restricts editing and printing permissions). The tool applies RC4-128-bit encryption — the standard format compatible with Adobe Reader and all major PDF viewers.
Tip: Use a strong password of at least 12 characters mixing letters, numbers, and symbols. Share the password via a separate secure channel (not the same email as the PDF).
Click Protect PDF and download the encrypted file. Anyone who opens it will be prompted to enter the password before the document is visible.
RC4-128-bit encryption, which is the industry-standard format supported by Adobe Acrobat, Apple Preview, and all major PDF viewers.
The user password is required to open the PDF. The owner password restricts permissions — such as printing, copying text, or editing — even after the PDF is opened. You can set just a user password, just an owner password, or both.
Yes. The encrypt process is fast even for large documents since it is processed locally in your browser without any server round-trips.
Yes — completely free at pdfeditor.onl/protect-pdf. No account, no upload limits, no watermarks.