Lock PDF

Password Protect Your Files Online Using Quick Cropper

Quick Cropper's Lock PDF tool puts a password on your PDF so only the right people can open it. Files are encrypted with AES-256, and you can block printing and copying too.

Lock PDF with Quick Cropper to password protect files online - free, with no account, no watermark and no copies of your files kept.

Why Lock Your PDF ?

PDFs often hold private information: bank details, salary figures, ID numbers and business prices. Once a file is sent, you can't control where it goes next. A password keeps the content safe even if the file is forwarded or a phone is lost, and restrictions let people read a document without printing or copying it.

Key Features of Lock PDF

Strong Encryption :
AES-256, supported by all modern PDF readers.
Strength Meter :
See how strong your password is as you type.
Restrictions :
Block printing, copying or editing.
Owner Password :
Change the restrictions later if you need to.
Private by Design :
Files are deleted right away; passwords are never saved.
Up to 50 MB :
Protect large PDFs with many pages.

How It Works

How Lock PDF Works

Locking a PDF takes just a few steps.

Add a PDF

Upload the PDF you want to protect.

Choose a password

Type and confirm a strong password.

Set restrictions

Optionally block printing, copying or editing.

Download

Save your password-protected PDF.

Quick and simple : Protect PDF files online without installing any software.

Benefits of Using Quick Cropper

Privacy :
Keep sensitive documents safe from the wrong eyes.
Control :
Decide who can print, copy or edit.
Simple :
Lock a PDF in a few clicks.
Free :
No sign-up and no limits.

Who Is It For ?

Everyone :
Bank statements, tax papers and ID proofs.
Sellers :
Invoices, price lists and supplier files.
Offices :
Payslips, contracts and reports.
Teachers :
Notes and papers that shouldn't be copied.

Quick Cropper makes protecting any PDF quick and free. Whether you send one statement a month or dozens of invoices a day, locking each file takes only a few seconds, and your customers or colleagues can open it in any PDF reader once they have the password. It is a simple habit that keeps private information private.

What a Password Protects

When you lock a PDF, the pages are encrypted, which means they are turned into unreadable data that only the correct password can turn back into text and images. Without the password, no PDF reader can show the content. Restrictions work a little differently: they tell PDF readers not to allow printing, copying or editing after the file is opened. Standard readers such as Chrome, Edge, Adobe Reader and phone PDF apps respect these settings, so they are a good way to share a read-only document with customers or students.

Tips for Safe Sharing

Separate Channels :
Send the file by email and the password by SMS.
Strong Passwords :
Use 12+ characters with letters, numbers and symbols.
Save It :
Forgotten passwords can't be recovered.
Test It :
Open the locked file once before sending.

To remove a password, use Unlock PDF, and to shrink files, try Compress PDF.

FAQ

Frequently Asked Questions

Find answers to common questions about Lock PDF.

Is the Quick Cropper Lock PDF tool free?

Yes. Password protect PDFs up to 50 MB for free, with no account.

Which encryption is used?

AES-256, the strongest encryption available for PDF files.

Can I stop people printing or copying?

Yes. Turn on restrictions and choose to block printing, copying or editing.

Is my file stored?

No. Files are deleted as soon as they are processed, and passwords are never saved.

Can a forgotten password be recovered?

No. Keep the password safe, because nobody can recover it.

Lock PDF with Quick Cropper to Password Protect Files Online