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Protect PDF
Add a password to keep a PDF's contents private.
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Protect PDF processes files locally in your browser.
Password-protect a PDF in your browser
Add a password to a PDF so only people who know it can open the file. Protection uses AES-256 encryption and runs entirely in your browser — no uploads required.
How to protect a PDF
- Select or drop a PDF.
- Enter a password.
- Confirm the password.
- Select Protect & download.
Browser privacy
- Encryption happens locally in the browser.
- Your file and password are not uploaded to Looty Tools.
Limits
- Maximum file size is 25 MB.
- Uses AES-256 encryption only — there is no algorithm choice.
- PDFs that are already password-protected are unsupported.
- If you lose the password, the file cannot be recovered — there is no backdoor.
Related PDF tools
- Merge PDFCombine multiple PDF files into one organized document.
- Split PDFExtract selected pages or separate a PDF into multiple files.
- Organize PDFReorder, rotate, duplicate, or remove pages from a PDF.
- Watermark PDFStamp text or an image watermark across PDF pages.
Guides
- How to Protect a PDFAdd a password to a PDF in your browser: choose a password, confirm it, and download an AES-256 encrypted copy that only your password can open.
- AES-256 PDF Encryption ExplainedUnderstand what AES-256 encryption means for a password-protected PDF, how it compares to older methods, and why a lost password cannot be recovered.
- Protect vs Unlock a PDFUnderstand the difference between adding a password to a PDF and removing an existing one, and what to do if your file already has a password.
Protect PDF FAQ
- Is my PDF or password uploaded when I protect a file?
- No. Protection runs locally in your browser using the Web Crypto API. Your file and password are never uploaded to Looty Tools.
- What encryption does Protect PDF use?
- AES-256, the modern PDF encryption standard (Standard Security Handler V=5, R=6). It is the strongest widely supported PDF encryption and is what current PDF security guidance recommends over older, weaker methods like RC4.
- What happens if I lose the password?
- There's no way to recover it. Looty Tools does not store your password, and there is no backdoor — treat the password like you would any other sensitive credential.
- Can I protect a PDF that already has a password?
- Not yet. Remove the existing password first (support for that is coming), then protect the file with a new password.
- Does protecting a PDF restrict printing or editing?
- No. Protect PDF only requires a password to open the file — it does not restrict printing, copying, or editing once the correct password is entered.
- What is the maximum file size?
- Protect PDF accepts one PDF up to 25 MB.
