Lock PDF Online Free - Add a Password to Protect Files

Add a Password to Protect Files Online with Free Lock PDF

Our lock PDF tool adds a password to any PDF so only the people you choose can open it. The file is encrypted with AES-256, the strongest protection the PDF format offers, and you can also block printing, copying or editing. It is ideal for bank statements, salary slips, contracts, ID proofs and any confidential document you send by email or WhatsApp.

This lock PDF tool to add a password and protect files for free works on any computer or phone. Lock PDF online free, add a password to protect files, and download the protected copy in seconds.

Why Password Protect a PDF ?

Emails get forwarded, phones get lost and shared folders are seen by more people than you expect. A password makes sure that even if the file reaches the wrong person, they can't read it. Banks, employers and government offices already send statements and payslips as locked PDFs for this reason. Locking your own documents gives you the same privacy, and restrictions let you share a document for reading while preventing people from printing or copying it.

Key Features of the Lock PDF Tool

AES-256 Encryption :
The same strong encryption used by banks, supported by every modern PDF reader.
Password Strength Check :
A strength bar helps you choose a password that is hard to guess.
Printing and Copying Restrictions :
Block printing, copying text and images, or editing and form filling.
Owner Password :
An optional second password that lets you change the restrictions later.
No Files Kept :
Your PDF is deleted as soon as it is locked, and the password is never stored.
Large Files :
Protect PDFs up to 50 MB with any number of pages.

How It Works

How to Lock a PDF

Upload a PDF, set a password and download the protected file.

Upload your PDF

Choose the PDF you want to protect (up to 50 MB).

Set a password

Type a password of at least 6 characters and confirm it. The strength bar shows how strong it is.

Add restrictions (optional)

Block printing, copying or editing, and add an owner password if you want to change them later.

Lock the PDF

Click Lock PDF. The file is encrypted with AES-256.

Download

The locked PDF downloads automatically. Keep the password safe and share it separately from the file.

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

Benefits of Locking PDFs

Keep Data Private :
Protect personal details like account numbers, PAN and Aadhaar.
Share Safely :
Send files by email or chat without worrying about forwarding.
Control Use :
Let people read a document without printing or copying it.
Look Professional :
Clients trust businesses that protect their documents.

Who Can Use This Tool?

Individuals :
Lock bank statements, tax returns, medical reports and ID proofs.
Businesses and Sellers :
Protect invoices, price lists, contracts and supplier documents.
HR and Accounts Teams :
Send payslips and salary letters that only the employee can open.
Teachers and Trainers :
Share notes and question papers that can't be printed or copied.

Whenever a PDF contains something private, a password is the simplest way to keep it that way.

How to Choose a Strong Password

Make It Long

12 or more characters are much harder to guess than 6 or 8.

Mix Characters

Use capital and small letters, numbers and a symbol.

Avoid the Obvious

Skip names, birthdays and 123456 - they are the first to be tried.

Tips for Sharing Locked PDFs

Send the Password Separately :
Email the file and share the password by SMS or a phone call.
Save the Password :
A forgotten password can't be recovered, so store it in a password manager.
Keep an Unlocked Copy :
Keep the original safely on your own device in case you need to edit it.
Test Before Sending :
Open the locked PDF once to check the password works.

To remove a password later, use Unlock PDF, and to make large files smaller before locking, try Compress PDF.

FAQ

Frequently Asked Questions

Find answers to common questions about password protecting PDF files.

Is this lock PDF tool free?

Yes. The PDF Cropper lock PDF tool is free with no sign-up and no watermark. Protect PDFs up to 50 MB.

How secure is the password protection?

PDFs are encrypted with AES-256, the strongest encryption the PDF format supports. Without the password, the pages can't be opened in any PDF reader.

Can I block printing or copying?

Yes. Tick Also restrict what people can do and choose to block printing, copying text and images, or editing. People can still open the PDF with the password but can't do the blocked actions in standard PDF readers.

What is the owner password?

The owner password lets you change or remove the restrictions later. If you leave it empty, a random owner password is used, so the restrictions stay in place.

What if I forget the password?

The password can't be recovered - not by us and not by the tool. Store it somewhere safe, such as a password manager, before sending the locked PDF.

Do you keep my file or password?

No. The file is processed and deleted straight away, and the password is never stored or logged.

Can I lock a PDF that already has a password?

Unlock it first with Unlock PDF, then lock it again with the new password.

Lock PDF Tool to Add a Password and Protect Files for Free

Lock PDF