Nouplo

Password-protect a PDF to share

Encrypt the file here, send it, and share the password over a different channel.

Drop files here

or click to choose from your deviceAccepted: PDF

One file per runUp to 20 MB per file5 runs per dayFree PDFs end with a small “Made with nouplo.com” lineRemove limits with Pro✓ Works offline

Your files stay on your device

This tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and you can even turn off your internet connection before you start.

Example

Example: emailing tax documents to an accountant, with the password given by phone

A self-employed designer (fictitious) scans her W-2 and 1099 forms into one PDF, 2026-tax-documents.pdf, to email to her accountant. Rather than her date of birth or the last four digits of her phone number, she uses a four-part passphrase.

  1. Drop 2026-tax-documents.pdf onto the box and type the password maple-orbit-canyon-47: 21 characters, easy to read out over the phone.
  2. Press Add password. The file is encrypted with AES-256 in the browser and downloads as 2026-tax-documents-protected.pdf.
  3. Attach that file to the email and say nothing about the password in it.
  4. Call or text the accountant with the password. Their PDF reader asks for it when the file is opened; typed exactly, the pages open, and can be printed and saved.
Password Why it is weak or strong
Date of birth, 03151988 About 36,500 dates in a century can be tried one after another, and many people know it
Last four digits of a phone number Only 10,000 combinations
Business name and year Anyone who has seen the email can guess it
maple-orbit-canyon-47 (example) 21 characters with no link to her: recommended

If the email is forwarded by mistake or a mailbox is broken into, the attachment alone cannot be read. Keep a note of the password: a PDF nobody can open cannot be recovered.

How it works

  1. Drop the PDF you are about to send: a contract, payslip, medical report or ID scan.
  2. Type a password. Use 12 or more characters, or a short phrase; the recipient will need to type it exactly.
  3. Press Add password. The file is encrypted with AES-256 in your browser and downloaded with -protected added to its name (contract.pdf becomes contract-protected.pdf).
  4. Attach it to the email or chat, then send the password another way: by phone, SMS or a different messaging app. Never in the same email.

Frequently asked questions

How strong is the protection?
The document is encrypted with AES-256, the strongest option in the PDF standard, and the same key is used as user and owner password. Without the password the content cannot be read and there is no recovery, so keep a copy of the password.
Why send the password separately?
If the email is forwarded or a mailbox is breached, an attacker gets both the file and the password in one place. Sending the password by phone or a second app means one leak is not enough. It also avoids the discredited habit of putting the password in the next email.
Can the recipient open it?
Yes. Acrobat Reader, Preview on Mac, Chrome, Edge, Firefox and the iOS and Android viewers all open AES-256 PDFs and prompt for the password. No extra software is needed, unlike password-protected zip files.
Does the password prevent copying or printing?
No. Once opened with the password the recipient has full rights, because the owner password is the same. For a visible deterrent, add the recipient's name with Watermark PDF before encrypting.
What makes a good password for a PDF I send?
Long and unrelated to you: three or four random words with a number, such as maple-orbit-canyon-47, give about 20 characters and are easy to read out over the phone. Avoid a date of birth or the last four digits of a phone number: there are only about 36,500 dates in a century and 10,000 four-digit endings, so they can be tried one after another.
Is my original file protected too?
No. A new file with -protected added to its name is downloaded; the original on your device stays as it was, without a password. Send the protected copy, and keep the original somewhere safe.
Is the PDF uploaded to Nouplo?
No. Encryption runs in your browser, so neither the document nor the password is transmitted. The free plan handles files up to 20 MB and 5 runs per day; Pro removes those limits.

Made for a specific use

Related tools

🔒 Protect PDF Encrypt a PDF with a password, or remove the password from one you own. ▬ Redact PDF Black out what must not be shared and have it actually gone from the file, without uploading the document. ◈ Watermark PDF Put a text stamp across every page so copies are clearly marked. ✎ Add text to PDF Click, type, drag into place. Fill in a form and sign it without the document leaving your device.