Protect PDF
Add a password to your PDF so only people with the password can open it.
Drop your PDF here, or click to select
Single PDF file · Max 100MB
Lock a PDF with a password before you send it
A protected PDF asks for a password the moment someone tries to open it. Until they type the right one, the file is encrypted bytes on disk — no preview, no thumbnail, no copy-paste. You set the password here, then share the locked file by email, chat, or a shared drive and hand over the password through a separate channel.
When a password actually matters
- Payslips and HR documents. Companies often mail each employee a salary slip or tax form. Locking each one means a forwarded or misdelivered email doesn't expose someone's income or ID number.
- Bank and investment statements. If you're submitting a statement for a loan or visa application, encrypting it stops it from being readable in transit or sitting unprotected in the recipient's inbox.
- Client deliverables and contracts. A signed agreement or proposal you don't want circulating beyond the people you sent it to.
- Medical and legal records. Anything you'd be uncomfortable seeing leak from a forwarded thread, or sitting unprotected in a cloud backup.
What "encryption" means here
This tool sets a user password (also called an open or document-open password) using AES encryption. AES is the same symmetric cipher used across the security industry; the strength comes from the password you choose, not the algorithm alone.
- 256-bit AES is the modern PDF 2.0 standard and what you should pick unless you have a reason not to. Every current reader — Acrobat, Preview on macOS, Chrome, Edge, most mobile viewers — opens it.
- 128-bit AES exists for compatibility with older software that predates the 256-bit spec. It's still strong; choose it only if your recipient is stuck on an ancient PDF reader.
The encryption keys are derived from your password, so a short or common password undermines even 256-bit AES. Use a long passphrase, and send it over a channel separate from the file.
Practical tips
- A passphrase of four unrelated words beats a short "complex" password and is easier to dictate over a call.
- Encryption doesn't compress; the protected file is roughly the same size as the original.
- Lock the file last. If you also need to merge, sign, watermark, or number pages, do that first — once the PDF is encrypted, other tools prompt for the password before they can touch it.
Limits and when to reach for a different tool
This tool sets the open password only. It does not configure granular owner permissions (allow printing but block copying, for example) — it locks the whole document behind one password. There's no password recovery: if you lose the password, the file is genuinely inaccessible, so save it before you share.
- Already have a locked PDF and know the password? Use Unlock PDF to remove the password (or strip print/copy restrictions) and get a clean copy back.
- Want to mark a document as confidential visually rather than encrypt it? Watermark PDF stamps DRAFT or CONFIDENTIAL across every page.
- Need to stop a filled form from being edited (not encrypt it)? Flatten PDF bakes the field values into the page.
- Adding your signature? Sign PDF stamps a drawn signature — do that before you protect the file.
How it works
- Upload the PDF you want to password protect.
- Enter a password, confirm it, and choose 128-bit or 256-bit encryption strength.
- Click Protect PDF to encrypt and lock the document.
- Download your password-protected PDF in seconds.
Frequently Asked Questions
Does this tool set granular permissions like allow-print but block-copy?
No. It sets only a single user (document-open) password that locks the whole file. Once someone enters it and the PDF opens, they can read, print and copy it like any normal document — there are no per-permission owner restrictions.
What is the difference between 128-bit and 256-bit encryption?
Both apply a strong AES open password. 256-bit AES is the modern PDF 2.0 standard and opens in every current reader, so pick it unless your recipient is on very old software; 128-bit exists only for compatibility with readers that predate the 256-bit spec.
Can I open or remove the password later if I set one?
Not without the password. It is the key the file is encrypted with, not a toggle. To remove protection you must already know the password and run the file through the Unlock PDF tool — there is no recovery if you lose it.
Does encrypting change my pages, quality or file size?
No. Your pages, text, images and fonts are untouched; only an encryption layer is added around them, so the output looks identical. Encryption doesn't compress, so the protected file is roughly the same size as the original.
Should I protect the PDF before or after merging, signing or watermarking it?
Lock it last. Once a PDF is encrypted, other tools prompt for the password before they can touch it, so do any merging, signing, watermarking or page numbering first, then protect the final file.