Encrypt PDF
Password-protect a PDF or remove its password entirely in your browser.
Encrypt PDF — Add a password to a PDF so it can only be opened by people who know it, or remove an existing password by unlocking the file and saving a clean copy. Everything runs in your browser with @cantoo/pdf-lib, so the document and the password are never uploaded to any server and stay completely private.
What is Encrypt PDF?
Encrypt PDF is a free, in-browser tool that either locks a PDF with a password or strips an existing password from one you can already open. People use Encrypt mode to protect contracts, payslips, statements, or any document before emailing or sharing it, and Decrypt mode to remove a password they already know so the file opens without a prompt. It loads the PDF locally, shows whether the file is already encrypted, and produces a new PDF you download — the original is left untouched.
How to use Encrypt PDF
- Drop a PDF onto the dropzone (or click to choose a file). The tool loads it locally and shows a first-page preview plus whether it is already encrypted.
- Choose a mode: Encrypt to add a password, or Decrypt to remove one you already know.
- Type the password in the Password field. For Encrypt this becomes the password needed to open the new file; for Decrypt enter the current password of the protected PDF.
- Check the status and output size, and preview the resulting first page.
- Click Encrypt & download (or Unlock & download) to save the new PDF. Use Reset to clear the file and start over.
Examples
Password-protect a contract before emailing
Drop contract.pdf, keep Encrypt mode, type a strong password, and click Encrypt & download. You get contract-encrypted.pdf, which now asks for that password whenever someone opens it.
Remove a password you already know
Switch to Decrypt mode, drop a protected file like statement.pdf, enter its current password, and click Unlock & download. The result statement-unlocked.pdf opens without any prompt.
Check whether a file is already encrypted
Drop any PDF and read the status line under the preview: it shows "Encrypted" for password-protected files and "Not encrypted" for open ones, so you know which mode to use.
Frequently asked questions
- Is my PDF or password sent to a server?
- No. Everything runs 100% client-side in your browser using @cantoo/pdf-lib. The document and the password you type are read and processed locally and are never uploaded, so even confidential files stay private.
- What's the difference between Encrypt and Decrypt?
- Encrypt adds a password so the new PDF can only be opened by someone who knows it. Decrypt takes a PDF you can already open with its password and saves a copy that opens with no password at all.
- I don't know the password — can it be cracked?
- No. Decrypt only removes a password you already know; you must enter the correct current password. This tool does not guess, brute-force, or bypass passwords on files you cannot already open.
- Why did I get a "wrong password" error?
- In Decrypt mode the password you entered does not match the one on the file. Re-check it (passwords are case-sensitive) and try again with the exact current password.
- Does it change my original file?
- No. The original is left untouched. The tool builds a brand-new PDF (named ...-encrypted.pdf or ...-unlocked.pdf) that you download separately.
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