You're about to email a client a signed contract, a payroll report or medical paperwork, and you want to make sure only the intended recipient can open it — even if the email gets forwarded or intercepted by mistake. That's what Protect PDF is for: it locks a PDF behind a password so it can't be opened without it. If instead you've received a password-protected PDF that you're authorized to open freely from now on, you want the Unlock PDF tool, which removes a password rather than adding one.
Step-by-step
- Open the Protect PDF tool, or click the "Protect PDF" card on the home page.
- Click the drop zone or drag in the PDF you want to protect.
- Type the password in the "Password" field and again in "Confirm password". Tick "Show password" if you want to check what you typed.
- Click "Process now." qpdf, running in your browser, encrypts the original document with AES-256 and sets your password both to open the file and to change its permissions.
- Your browser downloads protected.pdf. Its pages are untouched: text stays selectable and the file is about the same size as the original.
- Open protected.pdf yourself and confirm the password works before sending it to anyone. There is no password recovery.
- Share the password through a different channel than the file — a text message or a call if the PDF goes by email — so one compromised inbox doesn't expose both.
Common mistakes
- Forgetting the password. There is no recovery option and no backdoor: if the password is lost, the content is effectively gone. Store it in a password manager.
- Using a short or common password. AES-256 is only as strong as the password behind it, and a guessable password can be cracked offline. Use a long passphrase.
- Sending the file and the password in the same message. That defeats the purpose of protecting the PDF.
- Protecting a file that already has a password. The tool will ask you to unlock it first. Remove the old password with Unlock PDF, then protect it with the new one.
- Sending it to someone with a very old PDF reader. AES-256 is supported by every current reader, including browsers, Adobe Acrobat and phone apps, but readers from before 2008 may not open it.
FAQ
What encryption does PDF protection use on The PDFverse?
AES-256, the strongest encryption in the PDF standard. It's applied by qpdf, an open-source PDF library compiled to WebAssembly so it runs inside your browser. The same password is set as the password to open the file and as the owner password that controls permissions.
Can I recover a forgotten PDF password?
No. The PDFverse never sees or stores your password, and AES-256 has no backdoor. Save the password in a password manager before you close the tab.
Will my protected PDF still have selectable or searchable text?
Yes. The tool encrypts your original document as it is, without converting pages to images. Once the correct password is entered, the file is identical to the original: text, links, images and quality are all preserved, and the file size stays almost the same.
Is my file uploaded anywhere while it's being protected?
No. Encryption happens locally in your browser tab. Neither the file nor the password is sent to a server.
Checklist
- The file is a finished version; later edits should be made to the original and protected again.
- A long, unique password was typed twice and matches.
- The password is saved in a password manager or secure note.
- protected.pdf was opened with the password before sending.
- The password goes to the recipient through a different channel than the file.