pdf-toolsEncrypt a PDF Before Emailing It
Email was never designed to be private. If you're about to attach a sensitive PDF, encrypt it first. Why, how to do it in seconds, and what PDF encryption actually protects.
4 mins read
Loading tool…
What is the protect pdf?
Protect PDF adds a real open password with AES encryption to a PDF, sealing it locally with @cantoo/pdf-lib so any reader prompts for the password before showing a page. You set and confirm the password in your browser, which is never uploaded or stored. Free, watermark-free, with no server copy.
The GigAI PDF Protector adds a genuine open password to your document using AES encryption, all inside your browser tab with @cantoo/pdf-lib. Drop in one PDF, choose a password, confirm it, and the tool rewrites the file so that any reader (Acrobat, Preview, Chrome, a phone) asks for that password before showing a single page. Because the encryption happens locally, neither the file nor the password ever touches a server, so there is nothing to intercept, log or leak. The result is a standard encrypted PDF you can email, share or archive, safe in the knowledge that the contents stay sealed until the right password is entered.
- Difficulty:
- Easy
- Typical time:
- ~15s
- Processing:
- 100% browser processing
Last updated
How to use the protect pdf
- 1
Upload your PDF
Drag one PDF onto the drop zone, or click to browse. Only the file you want to protect is added: nothing is sent anywhere.
- 2
Set a password
Type the open password, then re-type it in the confirm field. Use the show/hide toggle to check it matches before you continue.
- 3
Encrypt
Hit Protect PDF. The tool encrypts the file with AES locally, so opening it will require your password from now on.
- 4
Download
Download the encrypted PDF and share it. Anyone who opens it, including you, will be prompted for the password first.
What Protect PDF includes
Real AES encryption
Your PDF is sealed with AES, the same encryption standard readers like Acrobat expect. Not a fake overlay. Without the password, the pages simply won't open.
Password never leaves your device
You type the password into your own browser and nowhere else. It's used locally to encrypt the file and is never transmitted, stored or recoverable by us.
100% in your browser
The whole file is encrypted on your device with @cantoo/pdf-lib. Nothing is uploaded, so there's no server copy of your document to worry about.
Confirm before you lock
A confirm field and a show/hide toggle mean you lock the file with exactly the password you intended. No silent typos that leave you locked out.
Opens anywhere
The protected PDF is a standard encrypted file. It prompts for the password in Acrobat, Preview, Chrome, Edge and mobile PDF apps alike.
Why use our protect pdf
Genuinely private
Encryption and the password stay on your device. There's no upload, no round-trip and no server-side copy: the sensitive part never leaves your browser.
You choose the password
No auto-generated codes to keep track of. Pick a password you'll remember (and can share safely), confirm it, and it's the exact key to the file.
Free with no watermark
No account, no daily cap and nothing stamped onto your pages. Protect as many PDFs as you need, whenever you need to, at no cost.
Works on any device
It's a normal web page. No install or plugin. Encrypt a PDF from a laptop, tablet or phone and get the same standards-based protected file.
Built for the way you work
From quick one-off fixes to daily workflows, see how people put this tool to use.
- Professional
Send a signed contract securely
Lock an executed agreement with a password before emailing it to the other party, so a forwarded or intercepted message can't expose the terms.
- Student
Protect a thesis draft before sharing
Add a password to an unpublished dissertation or research paper before sending it to a supervisor, keeping unreviewed work out of the wrong hands.
- Business
Distribute payroll and HR files
Encrypt payslips, offer letters or performance reviews so only the intended employee, holding the password, can open their own document.
Supported formats
Accepts PDF, and produces PDF (encrypted), all processed locally in your browser.
Input formats
Output formats
- PDF (encrypted)
Frequently asked questions
Use this in a workflow
See how the protect pdf fits into a step-by-step journey with related tools.
Recommended tools
Unlock PDF
Remove the open password from a PDF you own, enter the password, and download a decrypted copy you can read, edit and print. Free and 100% in your browser.
PDF Studio
Popular
Merge PDF
Combine multiple PDF files into a single document, drag to set the order, then download. Free, fast and entirely in your browser.
PDF Studio
Popular
Compress PDF
Shrink a PDF's file size right in your browser. Pick a compression level, see exactly how much you saved, and download. No uploads, no watermark.
PDF Studio
OCR PDF
Turn a scanned PDF into searchable, selectable text with in-browser OCR. Get a searchable PDF plus the extracted text: free, private, no uploads.
PDF Studio
Document Comparer
Compare two documents and see exactly what changed. Upload two PDF, Word, RTF, text or Markdown files and get a color-coded diff (additions in green, removals in red) with an added/removed count, all in your browser. Nothing is uploaded.
PDF Studio
New
Redact PDF
Permanently remove text from a PDF. Not a black box drawn on top. The words are destroyed, in your browser, and can't be selected, searched or recovered.
PDF Studio
Comparisons & guides
Go deeper on the concepts behind the protect pdf.
Guides & articles
- pdf-tools
- pdf-tools
How to Password-Protect a PDF
Adding a password to a PDF takes seconds, but doing it so the file is genuinely encrypted, and the password never leaks, is what actually matters. How to do it.
3 mins read 
pdf-toolsKeep Confidential PDFs Secure
Encryption is only one layer. Keeping confidential PDFs safe is a habit, a handful of practices that stop sensitive documents from ending up in the wrong
5 mins read
Common problems, solved
Hit a snag? Here are quick fixes for the issues people run into most.
My PDF won't encrypt. It says it may already be protected.
You can't add a password to a file that's already encrypted. Remove the existing password first with our Unlock PDF tool (you'll need to know it), then protect the unlocked copy with a new one.
The Protect button stays disabled.
You need a queued PDF and a password that matches its confirmation. Check the two fields are identical, the show/hide toggle helps, and that the password isn't empty or only spaces.
I forgot the password I set.
There's no back door. The encryption is real, so a lost password can't be recovered by us or anyone else. Always store it in a password manager, and keep the original unprotected file somewhere safe.
Get the most out of it
Use a long passphrase. A few unrelated words are far harder to crack than a short, complex password and much easier to remember.
Never send the password in the same email as the file. Share it separately, ideally over a different channel like a text or call.
Keep an unprotected master copy in a safe place. If you ever forget the password, the encrypted file can't be reopened.
Store the password in a password manager the moment you set it, so you and any intended recipient can retrieve it reliably.
Keep exploring
Problems we solve
Definitions
From the blog
Explore categories
Compare formats
By file type
Common tasks
Next steps
Your privacy is built in
Your PDF is encrypted entirely in your browser with @cantoo/pdf-lib, and the password you type is used only on your device to lock the file. Neither the document nor the password is ever uploaded, stored or logged: when you close the tab, both are gone.
- Runs in your browser
- No uploads
- Nothing stored
Ready to try the protect pdf?
Free, private and instant. Protect PDF runs right in your browser.