Protect PDF with a password

How to use it

1. Choose an unencrypted PDF or load the synthetic example.
2. Set a strong opening password and enter it again. Keep it separately: this tool does not provide password recovery.
3. Optionally enter a distinct owner password and choose reader permissions for printing, editing and copying. These permission flags do not provide the same protection as the opening password.
4. Create the protected PDF. Review the checked temporary clear preview and download protected.pdf; the downloaded file remains encrypted.
5. Open the saved PDF in your reader: a missing or incorrect opening password must fail, and the correct password must show the intended pages. Reset clears the current tool state.

Protect the synthetic four-page source with a new opening password. Reopening without that password must fail; entering it must preserve text, vector shapes, page rotation and cropping. A fresh export uses fresh cryptographic randomness.

Details & limits

Up to 25 MiB input/output and 100 pages; 60 seconds per operation. Signed PDFs, XFA, embedded files and active document actions are rejected. Checked JPEG and unfiltered/Flate images are supported within decoded-resource limits; inline images, JPEG 2000, JBIG2 and CCITT are unsupported. No PDF/A, PDF/UA or signature-validity certification. Passwords must contain 1–127 UTF-8 bytes and no line breaks or NUL. qpdf 12.4.1 loads about 2.25 MB on use; its WASM memory is capped at 512 MiB, excluding other browser memory. Already encrypted input must first be unlocked. Optional print/change/copy permissions rely on reader support. If no owner password is supplied, a separate random one is generated for this export.