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Add password protection and permission restrictions to your PDF documents.
Lock PDF is a free browser-based tool that helps you add password protection and permission restrictions to your pdf documents. It is part of ToolsMonk's pdf tools collection, so you can finish the job without downloading software, creating an account, or jumping between multiple websites.
This tool is especially useful for workflows such as password-protecting a confidential contract or statement before sending, restricting printing or copying of a document you share, and securing sensitive personal or business pdfs for storage. Because it runs directly in your browser, you can use it on desktop, tablet, or mobile while keeping the process fast and easy for one-off tasks as well as repeat work.
Lock PDF is also a strong fit for people searching for lock pdf, protect pdf, and password pdf, because it combines a simple interface with instant results and privacy-friendly processing.
Upload the PDF you want to protect
Set an open password and choose which permissions to restrict
Optionally enable a security stamp on each page
Apply protection and download the secured PDF
Add an open password so only people with it can view the PDF
Set permission restrictions — limit printing, editing, and copying
Optional security stamp on every page
Real encryption applied client-side, so your file is never uploaded
Works with standard PDF readers that honour the protections
Free, watermark-free (aside from your optional stamp), no limit
Password-protecting a confidential contract or statement before sending
Restricting printing or copying of a document you share
Securing sensitive personal or business PDFs for storage
Adding a layer of access control before emailing a file
Lock PDF is a powerful free online tool available on ToolsMonk that helps you add password protection and permission restrictions to your pdf documents. Whether you're a professional, student, or casual user, our lock pdf provides instant, accurate results right in your browser without requiring any software installation or account creation.
As part of our PDF Tools collection, this tool is designed with simplicity and power in mind. All processing happens client-side, ensuring your data remains completely private and secure. The tool works seamlessly across all modern browsers on desktop, tablet, and mobile devices.
Lock PDF secures a PDF with password protection and permission controls. You can require an open password to view the document at all, restrict what viewers may do (printing, editing, copying), and optionally stamp each page with a security mark — applied with genuine PDF encryption.
The two protections serve different purposes. The open password is the strong one: without it, the file simply won't open. Permission restrictions are softer — they tell compliant readers what's allowed once the file is open. For real confidentiality, set a long, unique open password.
Crucially for a security tool, the encryption is applied entirely in your browser, so your sensitive document is never uploaded. The flip side of real encryption is that there's no backdoor: if you lose the password, the file can't be opened, so store it safely and always keep an unprotected master copy.
Lock PDF pairs with Unlock PDF, which removes a password you know to produce an open copy. Together they let you protect files for sharing and reopen your own documents whenever you need to.
Use a long, unique open password and store it in a password manager — there's no recovery if you lose it
Always keep an unprotected master copy of the document for yourself
Set permission restrictions for casual control, but rely on the open password for real confidentiality
Common questions about this tool, its workflow, and what to expect before you use it.
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