Codrenix Toolbox logoCodrenix Toolboxby Codrenix

Protect PDF

Encrypt a PDF with a password using AES-256. Free and processed entirely in your browser — your file and password never leave your device.

All tools

Quick answer

Password protect a PDF free — add AES-256 encryption so only people with the password can open it. Built for professionals sending confidential documents and anyone safeguarding personal records. Encryption is applied in your browser; the file is never uploaded.

Drag & drop a PDF here

or click to browse files

PDF files only — up to 20MB each

Need to remove a password instead? Try Unlock PDF

How to password protect a PDF

  1. Upload a PDF

    Drag and drop the PDF you want to encrypt onto the tool.

  2. Set a password

    Choose a strong password; the strength indicator helps you judge it before you continue.

  3. Download the encrypted file

    Your browser protects the PDF with AES-256 locally and saves it. The recipient needs the password to open it.

Key features

AES-256 encryption

The same strong standard used by industry tools, applied locally before download.

You choose the password

Set it on the spot and share it through a different channel than the file itself.

Works in any PDF reader

Recipients get the standard password prompt in Acrobat, Preview, or their browser.

Supported formats

  • Input: PDF (.pdf), one file per operation
  • Output: encrypted PDF (.pdf) that requires the password to open

Privacy and security

Encryption runs entirely in your browser. The PDF and your chosen password are processed on your device; the password is never transmitted to us and the file is never uploaded. Use a strong password and share it separately from the file.

Limitations

  • One file at a time.
  • If you lose the password, the document cannot be recovered — there is no backdoor.
  • This adds an open password; it does not add digital-rights restrictions on printing.

Related Tools

All tools

Merge PDF

Combine multiple PDF files into one document in the order you want.

PDF ToolLive
Open Tool

Split PDF

Extract pages or split a PDF into separate files in a couple of clicks.

PDF ToolLive
Open Tool

Compress PDF

Reduce PDF file size while keeping quality — great for emailing.

PDF ToolLive
Open Tool

Frequently asked questions

Is my PDF uploaded to a server?

No. The password protection is applied entirely inside your browser using WebAssembly-speed JavaScript. Your file and your password never leave your device.

How strong is the encryption?

We use AES-256, the strongest standard encryption supported by the PDF format and the one recommended by the ISO 32000-2 specification.

What is the difference between the user password and the owner password?

The user password is required just to open and read the file. The optional owner password grants full access and controls permission restrictions like printing or copying. If you skip the owner password, only the open password is set.

Will the protected PDF open in Adobe Reader and Chrome?

Yes. AES-256 encrypted PDFs are supported by all modern viewers, including Adobe Reader, Chrome, Edge, Firefox, Preview and mobile viewers.