Password Protect a PDF

Put a password on a PDF so it can't be opened without one — or leave it readable but stop people printing and copying it. Real AES-256 encryption, done on your own device: the unprotected file is never uploaded anywhere.

Drop a PDF to protect

or click to choose a file

.pdf files · encrypted in your browser

AES-256 encryption
100% in your browser
No upload
No account

Why Put a Password on a PDF

A PDF travels further than you meant it to. It gets forwarded, re-attached, synced to a phone, backed up to a drive nobody audits. The share settings you set on the original folder stop at the first person who downloads it; a password is the one control that keeps travelling with the file.

That is why the documents people password protect a PDF for are so consistent: contracts and quotes, payslips and medical letters, board packs, and client deliverables that shouldn't be forwarded to a competitor. In each case the risk isn't the person you sent it to — it's the fourth person down the chain.

There is an awkward step in the usual way to password protect a PDF, though. To password protect a PDF with a typical online tool, you first upload the unprotected file to a stranger's server. That is precisely the copy you were trying to protect, handed over in the clear before it had any password on it at all. This tool doesn't ask for that: the encryption happens here, in your browser.

Open Password vs Permissions — Only One of Them Is Encryption

Password protecting a PDF encrypts its contents with a key derived from your password, so without that password the file is unreadable — not merely restricted.

When you password protect a PDF with an open password — the spec calls it the user password — that is real cryptography. The page contents and text strings are encrypted with AES-256, and a reader that doesn't have the password has nothing to show: not a blurred preview, not a locked-looking document, just bytes it can't turn back into a page.

The permissions password is a completely different thing wearing the same word. When you only restrict printing or copying, the file is encrypted with a key derived from a padding constant that is printed in the public PDF specification — so every PDF tool on earth already has the key before it starts. The restrictions themselves are a handful of flags in a field called /P, and honouring them is a matter of a program's manners. The specification says so in its own normative text: "There is nothing inherent in PDF encryption that enforces the document permissions specified in the encryption dictionary. Conforming readers shall respect the intent of the document creator." Shall respect the intent. Adobe's own products do; plenty of other software simply doesn't, and stripping the restrictions takes milliseconds and no password at all.

None of that makes permissions useless when you password protect a PDF — it makes them a Do Not Copy stamp rather than a lock. They state your intent, they stop the accidental print, and in some settings that intent carries weight of its own. Just don't rely on them against someone who has a reason to bypass them. If the document genuinely must not be read by the wrong person, use an open password.

About the encryption itself: the file is encrypted with a random 256-bit key, and your password only unwraps that key. This uses revision 6 of the standard security handler, the version introduced with PDF 2.0. That distinction matters more than it sounds — the earlier revision 5 reduced key derivation to essentially a single hash pass, which Adobe acknowledged made password guessing dramatically cheaper. Revision 6 restored a deliberately slow derivation, and it is the only revision PDF 2.0 has not deprecated.

How to Password Protect a PDF in 3 Steps

No software to install, no account, and no Acrobat licence. Here is how to password protect a PDF entirely in your browser — the file never gets uploaded, which on this particular tool is rather the point.

Open your PDF

Drag the file in or click to choose it. It opens on your device, and the page shows you which document you're about to lock.

Choose the protection

Pick how you want to password protect the PDF: an open password, restrictions only, or both. Type the password and confirm it, then switch off anything you don't want people doing — printing, copying, editing.

Protect & download

The PDF is encrypted with AES-256 and downloads straight away. Save the password somewhere safe first: there is no way to recover it.

Pro tip: Sending a draft that shouldn't be circulated? A visible mark says so on every page — add one with the watermark tool.

Restrict Printing, Copying and Editing

Six things you can switch off when you password protect a PDF. Printing stops the file going to paper or a PDF printer. Copying blocks text and image extraction. Editing covers changes to the content itself, commenting covers annotations and markup, forms covers filling in fields, and rearranging covers inserting, deleting or reordering pages. Leave a box ticked and that action stays allowed; untick it and the file asks readers not to do it.

Leave screen-reader access switched on. It is the one permission that costs a real person something: turning it off stops blind and low-vision readers from having the document read aloud, while adding essentially nothing to its security — anyone bypassing your restrictions is not going to be stopped by that particular flag. It stays on by default here, and if you do untick it the page will say so.

You can restrict a PDF without requiring a password to open it. That is the "Restrict only" mode: anybody can open and read the document, but it carries your instructions about printing and copying, and a permissions password you keep lets you lift them later. It is the right choice for a report you want widely read but not reused — and the wrong choice for anything genuinely confidential.

Why there's no RC4 or AES-128 option here. Other tools that password protect a PDF let you choose the encryption strength, offering 40-bit and 128-bit RC4 alongside AES. RC4 at either length has been broken for years, and AES-128 in a PDF derives its key through MD5. There is no situation in which picking one of those over AES-256 is the right answer, so this tool doesn't offer the choice. The one real cost is compatibility: AES-256 needs Acrobat X (2010) or a reader of similar vintage, so software older than that won't open the result.

Other ways to password protect a PDF, and their catches. The free Adobe Acrobat Reader cannot do it — password protection lives in Acrobat Standard and Pro, which is the single most common reason people go looking for something else. Microsoft Word can set a password when it exports, but it can't touch a PDF you already have. On a Mac, Preview genuinely can do it, free and locally, via File → Export with the Encrypt box ticked — worth knowing if you're on a Mac and would rather not use a website at all. Google Drive can't. Everything on this page happens in a browser tab, on any operating system, for free.

One thing that no attempt to password protect a PDF can do: stop the person who has the password. Once a document is open in front of someone, they can photograph the screen, retype it, or forward the password itself. Encryption controls who can open a file, not what an authorised reader then does with it.

Common ways people use it:

Contracts & quotes
Payslips
Board packs
Client deliverables
Stop printing
Stop copying
Without Acrobat

Password Protect a PDF on Any Device — Without Acrobat

You don't need Acrobat to password protect a PDF. The free Adobe Acrobat Reader can't do it at all — that feature is in Acrobat Standard and Pro. A browser can, on any operating system, with nothing to install and no account to create.

§ 01

Windows & Mac

Open the tool in Chrome, Edge, Safari or Firefox and encrypt the file locally. On a Mac, Preview can also do this offline via File → Export — use whichever you prefer.

§ 02

Chromebook & Linux

Acrobat has no desktop version here, which normally means uploading your confidential file to some website. This runs in the browser instead, so nothing leaves the machine.

§ 03

iPhone, iPad & Android

The whole thing works with touch, so you can password protect a PDF from your phone before forwarding it — no app to install.

How This Compares to Other Free PDF Password Tools

Of everything below, the last row is what matters most when you password protect a PDF. Every well-known free tool encrypts your PDF on its own servers, which means the unprotected file is uploaded first — the one copy you were trying to keep to yourself.

	This tool	iLovePDF	Smallpdf	PDF24	Sejda
Encryption used	AES-256 (R6)	Not stated	Not stated	Not stated	Not stated
Open password	Yes	Yes	Yes	Yes	Yes
Restrict without an open password	Yes	Not verified	Not verified	Not verified	Not verified
Per-permission switches	7	Not verified	Not verified	Not verified	Not verified
Free limits	None	2 files, 100 MB	Daily limit	None stated	3 tasks/hour, 50 MB
Is your file uploaded?	Never	Uploaded	Uploaded	Uploaded	Uploaded

Rows marked "not verified" are ones we haven't checked against the live tools rather than ones we're claiming to win — they'll be filled in as we confirm them. The upload row is verified: all four state in their own privacy copy that files are processed on their servers and deleted after an hour or two.

The Unprotected File Never Leaves Your Browser

Think about what the usual way to password protect a PDF actually asks of you. To get a password onto a confidential document, you upload that document — without the password — to a company you've never dealt with, and trust a line of text promising it will be deleted in an hour. For most tools that's a privacy preference. On a page about protecting files, it's a contradiction.

Here the encryption runs in your browser. The PDF is never uploaded, and neither is the password — it is used on your device to derive the key and then it's gone. We never hold your file in the clear, which is also why there is no sign-in, no daily quota and no file-size cap: there is nothing on our side to meter. Want proof? Load the page, turn off your Wi-Fi, and protect a file anyway. It still works, and your browser's Network panel shows zero file requests.

§ 01

No upload

The PDF is read and encrypted locally with in-browser code. It never travels to a server.

§ 02

Password stays local

Your password is used on your device to derive the encryption key. It is never transmitted or stored.

§ 03

No limits

Any file size, any page count, as often as you like. The only ceiling is your own device's memory.

Frequently Asked Questions

How do I password protect a PDF for free?⌄

To password protect a PDF for free, open it here, choose an open password, type it twice, and click Protect & download. It's free with no sign-up and no file-size limit, and the encryption runs in your browser rather than on a server.

Can I password protect a PDF with the free Adobe Acrobat Reader?⌄

No. Password protection is not included in the free Acrobat Reader — you need Acrobat Standard or Pro, both paid. That's the most common reason people look for a browser-based tool, and this one needs neither a licence nor an Adobe account.

What's the difference between an open password and a permissions password?⌄

An open password encrypts the file: without it, the contents can't be read at all. A permissions password only marks what readers are asked not to do — print, copy, edit — while leaving the document readable by anyone.

Can the printing and copying restrictions be removed?⌄

Yes, easily, and we'd rather say so. When there's no open password, the file's key comes from a constant published in the PDF specification, so any tool can already read it and drop the restrictions in milliseconds. Only an open password stops a file being read.

How strong is the encryption?⌄

This tool password protects a PDF with AES-256 using revision 6 of the standard security handler, the version introduced in PDF 2.0. The file gets a random 256-bit key and your password only unwraps it, so the practical strength comes down to how hard your password is to guess.

What happens if I forget the password?⌄

The file stays locked. There is no back door, no reset and no recovery — not by us, not by anyone. Save the password in a password manager before you download the protected file.

Will the protected file open on my phone or an old reader?⌄

It opens in any current PDF reader on desktop or mobile. AES-256 needs Acrobat X (2010) or newer, so genuinely old software won't open it — a fair trade for not using encryption that's been broken for years.

If I only restrict permissions, can people still open the file?⌄

Yes — that's what that mode is for. Anyone can open and read it; the restrictions only ask readers not to print or copy. Choose an open password if the document shouldn't be read at all.

Does protecting a PDF change its quality or size?⌄

Quality is untouched — nothing is re-encoded, and text stays text. The file grows by around ten percent, because encryption adds padding and an initialisation vector to each stream. Compress the PDF first if size matters.

Can I protect a PDF that already has a password?⌄

Not directly. You can't password protect a PDF that is already encrypted — it has to be unlocked first, so remove the existing password and then set the new one.

How do I remove password protection from a PDF?⌄

If you know the password, most PDF readers let you save an unprotected copy. If you only want to drop printing or copying restrictions, that needs no password at all — which is exactly why those restrictions shouldn't be relied on for anything sensitive.

Is my file or my password uploaded anywhere?⌄

No. The PDF is encrypted entirely in your browser and the password never leaves your device. You can disconnect from the internet after the page loads and it still works.

Password protect a PDF — free, private, no upload

Password protect a PDF with real AES-256 encryption, an open password or permission restrictions, and a file that never leaves your browser. No Acrobat, no account, no limits.

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