Encrypt PDF — Password Protect PDF Online
Lock your PDF with AES-256 encryption in seconds. Set a user password to control who can open the file, and an owner password to restrict printing, copying, or editing. Everything runs in your browser — the file and password never leave your device.
Why use this tool
AES-256 — the same encryption used by banks and governments
Many free 'PDF password' tools use outdated RC4 40-bit encryption that can be cracked in seconds. This tool applies AES-256, the algorithm mandated by US federal security standards (FIPS 197) and used in TLS, full-disk encryption, and banking systems.
Two independent passwords — open and edit restrictions
The user password controls who can open the document. The owner password restricts what recipients can do: print, copy text, or modify the file. You can set one or both independently depending on your use case.
Zero-knowledge — password never touches any server
Encryption runs entirely in the browser using the pdf-lib library. Neither your PDF nor your password is transmitted over the network. You can disconnect from the internet after loading the page and encryption still works.
How to encrypt PDF
- 1Upload your PDF file to the upload area
- 2Enter a user password (to open) and/or an owner password (to restrict editing)
- 3Click 'Encrypt'
- 4Download the password-protected PDF
Features
- AES-256 encryption — industry-standard security used by banks and governments
- Separate user password (open) and owner password (edit/print)
- Restrict permissions: disable printing, copying, and modifications
- Processed in your browser — your PDF never leaves your device
When it's useful
- Password-protect a salary report before emailing it to an employee
- Restrict printing on a copyrighted ebook PDF before distributing it
- Lock a medical record on a shared family computer so only authorized users can open it
Common problems
PDF opens without a password after encryption
Only the user (open) password blocks access. If you set only an owner password, the file opens freely — editing and printing are restricted, not opening.
Encrypted file won't open in Adobe Reader
Enter the user password, not the owner password. They serve different purposes and are not interchangeable.
Password was forgotten after encryption
AES-256 encryption cannot be brute-forced in reasonable time. Always store passwords in a password manager.
FAQ
What is the owner password?
The owner password restricts permissions — it prevents printing, copying text, and editing. The recipient can still open the file but cannot change it.
What encryption strength is used?
AES-256 encryption is applied — the same standard used by banks and government agencies.
Can I remove the password later?
Yes — use the 'Decrypt PDF' tool. You will need to know the original password.
What if I forget the password?
There is no way to recover a forgotten password. Always store your password in a safe place.
Can I restrict printing but still allow the file to be opened?
Yes. Set only the owner password — leave the user password blank. The file opens freely, but printing, copying, and editing are disabled. The user password controls opening; the owner password controls permissions.
Is a PDF password the same as a digital signature?
No. A password restricts access and permissions. A digital signature verifies the document's authorship and integrity. These serve different purposes and are often used together for sensitive documents.
Will the encrypted PDF open on any PDF reader?
Any modern reader that supports AES-256 will open it — Adobe Acrobat, Apple Preview, Foxit, and most mobile PDF apps. Readers from before 2009 may have issues with 256-bit encryption.
Can I set different passwords for different recipients?
Standard PDF encryption uses one password per document. For per-recipient access control, run the encryption separately for each recipient and send each person their own encrypted copy with a unique password.
Related Tools
Decrypt PDF
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Digital Sign PDF
Add a digital signature with SHA-256 hash to verify PDF integrity