Midnight Studio
Home / Tools / Protect PDF

Add a password to a PDF

Lock a PDF with strong AES-256 encryption so only people who know the password can open it.

Your files never leave your device

Files stay in this browser tab. Close the page and they are gone.

How it works

  1. Add the PDF.
  2. Type a password twice and choose what readers may do.
  3. Download the protected PDF.

Questions

How strong is the protection?

The PDF is encrypted with AES-256, the strongest standard PDF encryption, and opens in Adobe Reader, Chrome, Edge, macOS Preview and other common viewers.

What if I forget the password?

Nobody can recover it — not even us, because we never see your file or password. Keep the password somewhere safe.

Are my files uploaded anywhere?

No. The tool runs entirely in your browser, so your files never leave your device and nothing is kept after you close the page. You can check it yourself: once the page has loaded, turn on airplane mode — the tool keeps working.

Is it free? Is there a file limit?

Yes, it is free, with no sign-up and no watermark. There is no upload limit because nothing is uploaded; very large files are limited only by your device’s memory.

More free tools

Merge PDFCombine several PDFs into one, in the order you want.Compress PDFMake a PDF smaller so it fits email and upload limits.JPG to PDFTurn photos and scans into one tidy PDF.PDF to JPGSave every page of a PDF as a JPG or PNG image.Split PDFPull out the pages you need, or split a PDF into parts.Sign PDFDraw or upload your signature and place it on any page.Rotate PDFTurn sideways or upside-down pages the right way up.Delete PDF PagesRemove blank or unwanted pages from a PDF.Rearrange PDF PagesReorder, rotate and remove pages in one place.Add Page NumbersNumber the pages of a PDF, in the style you choose.Watermark PDFStamp text like “Confidential” or your logo across the pages.Crop PDFTrim the margins of PDF pages.