Free PDF Password Protector

Protect PDF is a free online tool that adds password protection to your PDF files to prevent unauthorized access.

Yes, it is completely free with no registration required. All encryption happens client-side in your browser.

Yes, all password protection is applied locally in your browser. Your PDF files and passwords are never sent to any server.

Yes, the PDF Password Protector is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the PDF Password Protector in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Since the PDF Password Protector processes files in your browser, the size limit depends on your device's memory. Most devices can handle PDFs up to 50-100MB without issues.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The PDF Password Protector works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

A PDF can carry two distinct passwords that do different jobs. The user password, sometimes called the open password, is what a reader types to view the document at all; without it, the file will not open. The owner password, also called the permissions password, controls the restrictions on the file -- printing, editing, copying -- and lets an administrator change or remove those limits later. A PDF can have an owner password even when anyone is allowed to open it freely. In this tool the user password is required and the owner password is optional, so you can lock the document fully or just govern what readers may do. One rule covers both: if you forget either password there is no recovery. Set your user and owner passwords here, store them in a password manager, and download the protected copy.

Both 128-bit and 256-bit AES are strong, widely trusted encryption standards; the number refers to the key length used to scramble the document. 256-bit AES uses a longer key, making it the more future-proof and harder-to-brute-force choice, which is why it is often labeled maximum security. 128-bit AES offers broader compatibility with older PDF readers and devices that may not support the newer standard, while still being extremely difficult to crack in practice. For most everyday documents either level is far beyond what an ordinary attacker could break. Choose 256-bit when you want the strongest available setting and your recipients use modern viewers; choose 128-bit if you need to support legacy software. This tool lets you pick either level on the Security tab before you process and download your file.

It applies real encryption. The tool runs qpdf -- the same open-source engine used in many server-side PDF pipelines -- compiled to WebAssembly so it executes inside your browser tab, with no native libraries and no upload required. It writes standard AES-128 or AES-256 encryption exactly as the PDF specification defines it, so any compliant reader such as Acrobat, Preview, Chrome or Edge will ask for your password before showing a single page. The permission flags you choose are written into the document's encryption dictionary at the same time. Because everything runs locally, your file and your password never leave your device; the only practical limit is your browser's memory on very large documents.

A strong password is long and mixes character types. The single most important factor is length, because each extra character multiplies the number of combinations an attacker must try; aim for at least twelve characters when the document is sensitive. Combine uppercase and lowercase letters, numbers, and symbols rather than relying on a single dictionary word, and avoid obvious choices like names, birthdays, or sequences such as 1234. A memorable passphrase of several unrelated words with a few substitutions is both strong and easier to recall. This tool includes a live strength meter that rates your user password from Weak to Strong as you type, scoring length and character variety so you can see instantly whether it is solid. The minimum accepted length is four characters, but eight or more with mixed types is far safer. Type your password above and watch the meter.

Beyond the open password, this tool lets you allow or deny several actions independently, so you can shape exactly what a reader is permitted to do once the file is open. Printing controls whether the document can be sent to a printer or saved as a paper or PDF copy. Copying text governs whether readers can select and copy content to paste elsewhere. Modifying decides whether the document's contents can be edited. Annotating sets whether readers may add comments, highlights, or markups. Form filling determines whether interactive form fields can be completed. Each toggles separately, so you can, for example, let people read and print a report while blocking copying and editing, or allow form filling on a document you otherwise lock down. Open the Security tab, set each permission to match how you want the file used, then process and download it.