Step 1: Upload your file
Drag and drop your PDF into the tool, or browse your computer's local disk to select it. There's no limit on file size, so a single-page form and a large multi-page contract both work the same way.
Set a password for your PDF
Your protected PDF is ready!
Drag and drop your PDF into the tool, or browse your computer's local disk to select it. There's no limit on file size, so a single-page form and a large multi-page contract both work the same way.
Once the file is uploaded, a password box appears. Enter the password you want applied, whether that's a fully custom one or a system-generated password with a strength indicator to guide you.
Hit convert and encryption is applied in seconds. Behind the scenes, PDF24 wraps the file in 256-bit AES encryption without touching the document's underlying content, fonts, or layout.
A download option appears once conversion finishes. From there, share the protected PDF with only the people you trust, knowing it can't be opened without the password you set.
PDF password protection isn't a single setting, and understanding the difference helps you apply the right kind for the job.
An open password (also called a user password) controls whether a file can be opened at all. Without the correct password, the PDF simply won't display, which is the right choice for anything that shouldn't be seen by unauthorized people in the first place, such as financial statements or medical records.
A permission password (also called an owner password) lets a file open freely while restricting specific actions once it's open, such as printing, copying text, or editing content. This is the setting behind the legal-contract use case above: a client can open and read a contract, but can't alter its terms without the permission password.
Protect PDF supports both approaches, so the right setup depends on whether you need to stop a document from being opened at all, or simply need to stop it from being changed once someone has access.
Your PDF files are protected with strong encryption during upload and processing. Once the protection process is complete, uploaded files are automatically deleted from our servers to help keep your documents private and secure.
Adding password protection does not affect your PDF's content, formatting, images, fonts, or layout. Your document keeps its original appearance while gaining an extra layer of security.
Customize your document protection by applying password security and other available protection settings. These options help you control who can access your PDF while keeping the original file intact.
A clean, user-friendly interface with step-by-step guidance makes protecting PDFs quick and easy. Simply upload your file, set a password, and download the secured document in just a few clicks.
Protect PDFs of virtually any size with fast and reliable performance. Whether you're securing a single-page document or a large report, the tool delivers consistent results across all devices and browsers.
Password-protect bank statements, invoices, tax returns, and other financial documents before emailing or sharing them. This helps keep sensitive financial information secure during storage and transmission.
Protect business reports, executive summaries, HR files, and internal documents with a password so that only authorized users can open and view them.
Secure legal agreements, contracts, and confidential documents with password protection before sharing them with clients, partners, or legal teams.
Protect personal documents such as medical records, identification documents, certificates, and insurance papers before storing them in cloud storage or sharing them with family members.
Secure draft books, research papers, design concepts, presentations, and other creative projects with a password to prevent unauthorized access before publication or client approval.
“Securing” a PDF can mean a few different things, and picking the wrong tool wastes time.
(This tool) restricts who can open a file at all, by requiring a password before the document will open. It doesn't change what's inside the PDF, it changes who can get in.
adds a digital or electronic signature to a document, useful for approvals and legally binding agreements. A signed PDF can still be opened by anyone with the file; signing verifies who approved it, it doesn't restrict access the way a password does.
permanently removes specific sensitive content, such as account numbers or names, before a document is shared more broadly. Redaction changes what's visible in the file itself, rather than controlling who can open it.
A quick way to decide: if you want to stop unauthorized people from opening a file at all, use Protect PDF. If you need to approve or formalize a document, use Sign PDF. If specific information inside the file needs to disappear before it's shared, use Redact PDF.
“Securing” a PDF can mean a few different things, and picking the wrong tool wastes time.
● Avoid reusing a password from another account. If the PDF is ever shared more widely than intended, a unique password limits the damage.
● Longer passwords with a mix of letters, numbers, and symbols resist brute-force attempts far better than short, predictable ones, even with 256-bit AES encryption doing the heavy lifting underneath.
● If the protected PDF is also large in file size, running it through Compress PDF before or after protecting it can make it easier to email, without weakening the password protection applied.
● Store the password somewhere separate from the PDF itself. A password kept in the same email thread as the protected file defeats much of the purpose of protecting it.
Yes. Protect PDF is completely free to use with no hidden charges, subscriptions, or limits on how many PDF files you can protect.
Your PDF is protected using strong encryption to help prevent unauthorized access. A secure password adds an extra layer of protection when sharing or storing sensitive documents.
No. Applying password protection does not modify your PDF's content, formatting, fonts, images, or layout. Only access to the document is restricted.
If you've forgotten your password, you'll need to recover or remove it using a compatible PDF password recovery or unlock tool. Be sure you have permission to access the protected document before attempting to unlock it.
Upload your PDF above, create a strong password, and protect your document in just a few seconds.
“Securing” a PDF can mean a few different things, and picking the wrong tool wastes time.
● Confirm the live hero subheadline is replaced (currently describes converting images to PDF, not password protection; see Dev Notes bug flag).
● Confirm the CTA button text and destination are corrected from "Try PDF to Images Today" to a Protect PDF specific CTA.
● Confirm the FAQ answer for "Will the Integrity and Quality of My PDF Be Compromised?" is replaced with content that actually answers the question (see Dev Notes bug flag).
● Confirm target URL matches the live slug exactly: https://pdf24.ai/protect-pdf (no /en/ prefix).
● Verify all internal links resolve: /unlock-pdf, /compress-pdf, and the confirmed slugs for Sign PDF and Redact PDF.
● Confirm the General Questions About PDF24 block is removed from this page and replaced with a single link to /documentation.
● Confirm FAQPage structured data reflects only the four tool-specific FAQ entries, not the removed general block.
● Verify Section 3 (body copy only) is 1,300+ words: extract Section 3 to plain text and run wc -w on it directly, separate from the full-document pandoc count.
● Spot-check the Protect vs. Sign vs. Redact section against the live Sign PDF and Redact PDF pages for consistency once those pages are drafted.
● Proofread for em dashes (should be none) and confirm tone matches approved style (no fluff, no AI-sounding phrasing).