How to lock a PDF file without Acrobat?

Use Convertify4u: drag your file, set a passphrase, save. Lock PDF with password in any modern browser — no desktop install.

Can I add password to PDF free?

Yes. Standard-sized PDFs lock free with no signup. Files over 100MB require Premium via Lemon Squeezy.

How strong is encrypt PDF with password here?

We apply PDF-standard AES-128/256 or RC4 via pdf-lib. Choose a long, unique password — encryption strength follows industry PDF security models.

Does my file go to your servers?

No. All processing is local. When you set password for PDF files here, bytes never leave your device.

What if I forget the password?

PDF passwords cannot be recovered by design. Keep a backup of the unprotected original before you create password protected PDF output.

Protect PDF Cluster

Add Password to PDF — Lock & Encrypt

Q: How to add password to PDF online?

Open this page, select your PDF locally, enter a password, and download. pdf-lib encrypts in a Web Worker — your file never uploads.

Need to add password to PDF before sharing? Set password for PDF opens, create password protected PDF output, and make PDF password protected in seconds — protect PDF with password using bank-level AES/RC4 encryption locally. Learn how to add password to PDF online and how to lock a PDF file without uploading your document.

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Need the main tool? Protect PDF

How it works

1
Select your PDF locally
Choose a file from your device. pdf-lib in a Web Worker parses pages — add password to PDF free with zero server transmission.
2
Enter your lock password
Type a strong passphrase to password secure PDF content. Encrypt PDF with password using PDF-standard AES or RC4 — lock PDF with password in one step.
3
Download the locked file
Save your create password protected PDF result instantly. Basic locks are free; massive files need Premium via Lemon Squeezy.

Use cases

Lock financial statements

Protect PDF with password before emailing quarterly reports — recipients need the passphrase to open.

Secure signed contracts

Create password protected PDF copies of executed agreements for archive storage.

Child-safe document sharing

Make PDF password protected so only parents can open school records saved on a shared tablet.

One-off confidential sends

Lock PDF with password for a single client attachment — add password to PDF online in under a minute.

Problems we solve

Print-to-PDF is not encryption

Saving as PDF does not lock content. You need real encrypt PDF with password via pdf-lib — not a visual-only restriction.

Upload privacy risk

Cloud tools retain copies. Local processing means set password for PDF workflows without transmission.

Forgotten lockouts

PDF passwords are irreversible. Always backup the original before you make PDF password protected.

Trust & privacy

Real PDF encryption

Password secure PDF files with AES/RC4 per specification — not a superficial viewer block.

100% on-device

Add password to PDF online while bytes stay in your browser — no cloud retention.

Free standard locks

Everyday password protection costs nothing. Premium handles batch and 100MB+ files.

Frequently asked questions

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