Protect PDF — Password-Encrypt in Your Browser
Password-protect a PDF in your browser before you email or share it—nothing is uploaded to a server. Steps: choose a PDF, enter and confirm a password (empty passwords are rejected), click Protect, then Download protected.pdf. Example: a one-page sample is encrypted with password sample and Download is enabled. This is standard user-password encryption—not military-grade; opening later needs that password (see Unlock PDF when we ship it). Files over ~25 MB may be slow.
How it works
Choose one PDF, type a password twice so they match, click Protect, then Download. Encryption runs in this tab after the PDF library loads. Reject empty passwords before encrypting.
Rules you should expect
Password rules, encryption scope, privacy, and failure cases for local PDF protection.
- Password: required; confirm field must match. Empty passwords are rejected before encrypt runs.
- Encryption: the PDF library sets user and owner password to the same value—viewers need it to open the file.
- Output: one encrypted PDF (protected.pdf). Already encrypted inputs fail with a clear message.
- Privacy & limits: bytes stay in the tab; not military-grade; ~25 MB soft warning; huge files may fail in memory.
Example
Sample builds a one-page PDF, encrypts it with password sample, enables Download for protected.pdf, and shows sample in the status line.
Good fits
- Office: add an open password before emailing a contract or payroll export.
- Ops: lock a one-off report PDF before sending it to a client portal.
- Students: protect a scanned assignment with a password only your instructor knows.
Frequently asked questions
Is my PDF uploaded?
No. The PDF library runs in your tab (scripts may load from a CDN). Your PDF is not uploaded to our servers.
How strong is the encryption?
It applies normal PDF user-password encryption so viewers must enter the password to open. It is not marketed as military-grade—pick a strong password you will remember.
How do I open the file later?
You need the same password you set here. When our Unlock PDF tool is available, use it with the password you chose—this site does not crack or bypass passwords.
What if the PDF is already protected?
Already encrypted files usually fail to load. Remove the old password with a tool you trust, then add your new password here.
Related tools
Questions or feedback
Something unclear, broken, or missing? Draft a message below — we read every note about these tools.