Encrypted in your browser, checked before download
Protect PDF Online — add a password with AES-256 encryption
Set a password that is needed to open the PDF, limit printing, copying and editing, or both. The file is encrypted in this browser tab, and the result is test-opened with your password before you download it.
- File and password stay in your browser
- AES-256, AES-128 or RC4
- Print, copy and edit limits
- Change an existing password
Add a password to your PDF
Add a PDF, set an open password, limits or both, then save a protected copy.
Drop your PDF here
or browse — one PDF, any number of pages
Passwords
Encryption and limits
Good to know
Your pages
Check it's the right file before you protect it. Click a page to see it full size.
How it works
Real PDF encryption, not a viewer setting
Every text string and stream in the file is encrypted with the standard PDF security handler, the same format Adobe Acrobat writes. Before you download, the saved file is opened in this browser to check it asks for the password and opens with yours.
What you can do
- Require a password to open the PDF, encrypted with AES-256, AES-128 or RC4.
- Limit printing, copying and changes, with a separate permissions password.
- Change the password or limits of a PDF that is already protected, with any standard encryption.
- Keep pages, text, links, bookmarks, form fields and document properties as they are.
What it doesn't do
- Recover a lost password. If you forget the open password, the file can't be opened, by us or anyone.
- Force limits on every app. Printing and copying limits are honored by standard readers, but software that ignores them can still print or copy.
- Remove limits set by someone else. Changing a protected file's limits needs its permissions password.
- Keep a digital signature valid. Encrypting rewrites the file, so signatures show as invalid.
How to password-protect a PDF in four steps
Add, set passwords, choose limits, save.
Add your PDF
Drop the PDF onto the upload area, or click Select PDF. If it already has a password, enter it to change the protection.
Set the open password
- Type it twice; the eye button shows it.
- The strength line tells you if it's easy to guess.
Add limits if you need them
Tick Limit printing, copying and editing, set a different permissions password, and choose what's allowed.
AES-256 suits almost everyone; pick AES-128 only for very old Acrobat versions.
Protect and download
Click Protect PDF. The result shows the checks it passed and a preview opened with your password.
What to set for your job
Common reasons to protect a PDF and the settings that fit.
| Job | What matters | What to set |
|---|---|---|
| Email a payslip, statement or ID copy | Only the person you send it to can open it. | Open password, AES-256. Send the password by a different channel, such as a text message. |
| Share a contract for reading only | It can be read, not changed. | Limits on, Changes: Not allowed, copying off; open password optional. |
| Send a form to be filled in | Fields can be filled; the layout can't be edited. | Limits on, Changes: Fill in forms and sign. |
| Hand out a draft | No clean high-quality prints. | Limits on, Printing: Low resolution only. |
| Archive personal records | Unreadable if the drive is lost. | Open password of 12 or more characters, AES-256; store it in a password manager. |
| Change an old password | New password, same file. | Add the file, enter the current password, set the new one. |
The details
What each setting actually does
So you know what the protection does and doesn't guarantee.
Open password
Without it the content can't be decrypted. Its strength is what protects the file: a long password with mixed characters is much harder to guess.
Permissions password
Needed to change the limits. It must differ from the open password; otherwise anyone who can open the file could lift the limits.
Limits
Printing, changes, copying and screen-reader access are flags that standard PDF readers obey. They guide honest software; they are not a lock.
AES-256
The current PDF standard (security handler revision 6), with a slow password check that makes guessing expensive. Supported since Acrobat X.
AES-128 and RC4
Older formats for older readers. Their password check is fast to attack, and RC4 itself is broken; use them only when a reader can't open AES-256.
The rest of the file
Pages, text, links, bookmarks, form fields and document properties are kept. Document properties are encrypted too, so the title can't be read without the password.
When something doesn't work as expected
Identify the problem, then use the matching fix.
"The two passwords don't match"
The second box has a typo, or Caps Lock is on.
Use the eye button to see what you typed, then type the second box again.
"AES-128 passwords can only use Latin letters"
Older encryption can't store letters like ગ or ह, and only reads 32 characters.
Choose AES-256, which takes any characters.
"The permissions password is needed"
The file has limits set with a permissions password, and you entered only the open password.
Enter the permissions password, or ask the person who protected the file.
An old app won't open the file
It predates AES-256 (Acrobat 9 and older, some old e-readers).
Protect the original again with AES-128.
Someone could still print
Their app ignores PDF limits, or they used the permissions password.
Rely on the open password for privacy; limits are guidance for standard readers.
"This PDF uses certificate security"
It is locked to a digital ID, not a password.
Open it in Adobe Acrobat with the digital ID and remove that security there.
Protecting without locking yourself out
A working order that avoids the most common problems.
Save the password first
Put it in a password manager before you download. A lost open password can't be recovered.
Use a passphrase
Four or more unrelated words, or 12+ mixed characters, are far harder to guess than a short word with a number.
Send the password separately
Email the file and text the password, so one leaked message doesn't expose both.
Finish the file first
Merge, compress, sign or edit before protecting; most tools need the password removed to work on an encrypted file.
Use two different passwords
With limits on, keep the permissions password to yourself and share only the open password.
Keep an unprotected original
Store it somewhere safe, so you can protect it again with other settings.
Protect PDF questions
If something's not covered here, the troubleshooting section above likely has it.
Is this real encryption or just a viewer lock?
It is real encryption. Every text string and stream in the PDF is encrypted with the standard PDF security handler that Adobe Acrobat also uses, and the saved file is opened in your browser to check that it asks for the password and opens with yours before you download it.
Which encryption should I choose?
AES-256 for almost everything: it opens in Adobe Acrobat X and newer and in all current browsers and PDF apps. Choose AES-128 only if someone uses Acrobat 9 or older, and RC4 only for very old readers, because it is weak.
What is the difference between the open and permissions passwords?
The open password is needed to read the file. The permissions password is needed to change the limits on printing, copying and editing. Use two different passwords, and share only the open password.
Can I change the password of a PDF that is already protected?
Yes. Add the file and enter its current password; RC4, AES-128 and AES-256 files all work. If the file has limits set with a permissions password, that password is needed to change them.
Do printing and copying limits stop everyone?
No. Standard PDF readers obey them, but software that ignores PDF limits can still print or copy. For privacy, rely on the open password.
What if I forget the password?
The file can't be opened without the open password; it can't be recovered by us or anyone else. Save it in a password manager before you download, and keep an unprotected original.
Is my PDF or password uploaded?
No. The PDF is encrypted in your browser with pdf-lib and the browser's built-in cryptography; neither the file nor the password is sent to our server.