How to use it
- Tap “Select PDF” and choose the file.
- Type a password, then type it again. Tap the eye icon to check what you typed.
- Optional: tick “Block printing”, “Block copying” or “Block editing” and set a separate permissions password.
- Tap “Protect PDF”, then “Download PDF”. Open the new file once to check the password works.
Real encryption: AES-256
The PDF is encrypted with AES-256, the strongest method in the PDF standard (ISO 32000-2). Without the password the pages can't be read at all — not in a viewer, not by opening the file another way. Adobe Acrobat Reader, Chrome, Edge, Firefox, Mac Preview and the PDF viewers on most Android phones and iPhones open it once the password is typed. PDF software older than about 2010 may not.
Open password vs restrictions
| Open password | Restrictions | |
|---|---|---|
| What it does | Encrypts the file; it won't open without the password | Asks PDF apps to block printing, copying or editing |
| How strong | As strong as your password | Followed by Adobe Reader, Chrome and most apps — but some apps ignore it |
| To change it later | The open password | The separate permissions password |
Restrictions are optional. Use them to discourage casual copying or printing, not to protect secrets — for that, the open password is what counts.
If you forget the password
Nobody can recover it — not ToolDabba, not the PDF app makers. That's what makes the encryption worth having. Write the password down somewhere safe, and keep your original, unlocked file if you might need it later.
Choosing a good password
- Length matters most: 12 or more characters, such as three unrelated words with a number.
- Avoid your date of birth, mobile number or a name + year pattern — anyone who knows you can guess those. (e-Aadhaar uses exactly that pattern, which is why it isn't hard to open.)
- Send the password separately — if you email the PDF, share the password by phone call or SMS.
Your PDF stays the same inside
Only encryption is added. Pages, text, images, links and form fields are unchanged, and the file grows by just a few kilobytes. To take the password off again later, use Unlock PDF with the same password.
Private by design
The file is encrypted inside your browser. Neither the PDF nor your password is uploaded or stored anywhere.