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PDF • Up to 20 MBEverything You Need to Secure Your PDF
Professional PDF protection tools with a seamless, modern experience.
Password Protection
Set a user password to prevent unauthorized access. Only people with the password can open the document.
Permission Controls
Fine-tune what recipients can do with your PDF — restrict printing, copying, editing, and form filling.
AES Encryption
Choose between 128-bit (compatible) or 256-bit (maximum security) AES encryption for your document.
Password Generator
Generate cryptographically strong passwords with one click. Includes a visual strength meter.
Instant Processing
Your PDF is protected in seconds using your device's processor — no server queues or upload delays.
100% Private
Your documents are processed locally in your browser. Nothing is uploaded or stored on our servers.
How to Password Protect a PDF Online
Three simple steps — no software installation required.
What Is PDF Password Protection?
PDF password protection is a security feature that encrypts your PDF document so only authorised recipients with the correct password can open or interact with it. There are two types of passwords in a PDF: an open (user) password that controls who can view the file, and an owner (permissions) password that controls what authorised users can do with the document — such as printing, copying text, or making edits.
Why Protect a PDF with a Password?
PDFs are one of the most widely shared document formats in the world — used for contracts, invoices, research papers, financial reports, and more. Without protection, anyone who receives the file can read, copy, edit, and redistribute its contents freely. Password protection prevents unauthorized access and misuse.
Common use cases include protecting confidential business documents, securing legal contracts before digital signing, protecting intellectual property from copying, and ensuring sensitive personal information cannot be altered or distributed.
Is My PDF Secure Using This Tool?
Yes. Our Protect PDF tool processes your document entirely within your web browser using the open-source pdf-lib library. Your file is never sent to any server — it is read locally, encrypted with AES-128 or AES-256 encryption, and the protected copy is offered for immediate download. Once you close the tab, all traces of your document are removed from browser storage automatically.
Frequently Asked Questions
Everything you need to know about protecting PDF files online.