How it works
Add your PDF
Drop one PDF into the box. It is read locally — nothing is uploaded, ever.
Set a password
Type a password twice on the Protect tab — or enter the current password on the Unlock tab.
Download
The qpdf security engine encrypts (or decrypts) your file right in your browser with AES-256.
Tips
- Use a real password. AES-256 is only as strong as the password — use 12+ characters you do not reuse elsewhere.
- Wide compatibility. Protected PDFs prompt for the password in Adobe Reader, Chrome, phones and tablets.
- No recovery exists. If you forget the password, there is no way to open the file again — store it in a password manager.
- Unlock before editing. Most PDF tools cannot open protected files — unlock first, then merge, split or compress.
Frequently asked questions
How do I password protect a PDF?
Add your PDF, type a password (twice), and hit Protect PDF. Your file is encrypted with AES-256 right in your browser — anyone opening it will need the password.
Is my password sent to a server?
No — and that is the whole point. Both your PDF and your password stay on your device; the encryption runs locally, so there is no server copy of either to worry about.
What encryption does EzySize use?
AES-256 encryption — the same cipher standard trusted by banks and governments — applied with the widely used qpdf engine, running entirely in your browser.
Can I remove a password from a PDF I own?
Yes — switch to the Unlock tab, add the protected PDF, enter its password, and download the unlocked copy. You must know the current password; there is no way to crack a forgotten one.
I forgot my PDF password — can this tool recover it?
No. AES-256 cannot be brute-forced in any practical timeframe, and there is no backdoor — everything runs in your browser and your password never leaves your device. Keep your password somewhere safe.
Will the protected PDF open everywhere?
On all modern readers — Adobe Acrobat/Reader, Chrome, Edge, Firefox, Safari and current phone and tablet apps — yes: they prompt for the password normally. Very old PDF readers may not understand AES-256 encryption, so if someone cannot open the file at all, an outdated reader is the likely cause.