Password-protect a PDF — on your device
Encrypt a PDF with AES-256 so it opens only with your password. Encryption happens in this tab; neither the file nor the password is sent anywhere.
Free forever · Runs on your device · 0 bytes uploaded
A forgotten password cannot be recovered. Keep it somewhere safe.
Speed depends on your device; big files on phones take longer. Slow or not working? Report it on GitHub
How to protect PDF
- Add one PDF file.
- Type a password twice.
- Click “Protect PDF” and download the encrypted copy.
Also good for
- add a password to a PDF
- encrypt PDF with AES-256
- lock a PDF file
- password protect PDF without Acrobat
- secure PDF before emailing
Private by design — and you can check
Your files are never uploaded, because there is nowhere to upload them to.
- No upload step existsFiles are read and written inside this browser tab. There is no server that could receive them.
- The browser enforces itThis page’s Content Security Policy only allows connections back to this site, which serves nothing but the app itself.
- See for yourselfOpen developer tools, watch the Network tab and run a job: no request carries your document.
- Open sourceEvery line is on GitHub, built on qpdf, pdf.js & pdf-lib.
Frequently asked questions
Are my files uploaded anywhere?
No. Fizzdoc does the work inside your browser tab, using open-source engines compiled to WebAssembly and JavaScript. Your file is read from your device, processed locally, and the result is saved straight back to your device. You can check this yourself: open your browser’s developer tools, go to the Network tab, and run a job — no request carries your file.
How strong is the protection?
Fizzdoc uses AES-256, the strongest encryption the PDF standard defines, via the qpdf engine. It opens in every modern PDF reader, including Adobe Acrobat, Chrome, Edge, Firefox and Preview.
What if I forget the password?
It cannot be recovered — not by Fizzdoc, not by anyone. Keep the password somewhere safe, such as a password manager.
Is Fizzdoc free?
Yes, and it stays free: no sign-up, no watermark, no daily limit and no premium tier. Fizzdoc is open source under the Apache-2.0 license, so anyone can run their own copy.
More private tools
- Merge PDFCombine several PDFs into one, in the order you choose.
- Split PDFExtract the pages you need into a new PDF.
- Rotate PDFTurn sideways pages the right way, permanently.
- Delete PDF PagesRemove pages you don’t want to share.
- Unlock PDFSave a copy without the password you know.
- Unlock Aadhaar PDFRemove the password from your e-Aadhaar PDF, on your device.
- Unlock e-PAN PDFRemove the password from your e-PAN card PDF.
- Unlock Bank Statement PDFRemove the password from a bank or credit card statement PDF.