Free, runs entirely in your browser — no sign-up, no file upload to a server.
What does Protect PDF do?
It adds password protection to a PDF, so it can only be opened with the password you set.
How strong is the encryption?
It uses the encryption built into the pdf-lib library's standard PDF security handler. For highly sensitive documents, pair this with your own judgment about where you store and send the protected file.
Where is my file processed?
Entirely in your browser — your file and the password you set are never uploaded anywhere.
How do I report a problem or request a feature for this tool?
Use the Contact / Feedback page — select "Protect PDF" as the related tool so we know exactly which tool you mean, then describe the bug or the feature you'd like to see.